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update with chapter 4-6 exercises
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‎exe4.ipynb

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{
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"cells": [
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.1\n",
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"import random\n",
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"S = [random.randint(0,100) for i in range(15)]\n",
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"\n",
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"def findmax(S, index):\n",
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" if index==len(S)-1:\n",
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" return S[index]\n",
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" else: return max(S[index], findmax(S, index+1))\n",
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" \n",
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"\n",
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"print(S)\n",
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"print(findmax(S, 0))"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.2\n",
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"def power(x,n):\n",
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" if n==0:\n",
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" return 1\n",
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" else: \n",
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" return x*(power(x,n-1))\n",
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"\n",
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"\"\"\"\n",
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"given x=2, n=5\n",
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"\n",
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"power(2,5) --> 2*16 = 32\n",
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" power(2,4) --> 2*8 = 16\n",
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" power(2,3) --> 2*4 = 8\n",
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" power(2,2) --> 2*2 = 4\n",
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" power(2,1) --> 2*1 = 2\n",
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" power(2,0) --> 1\n",
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"\"\"\"\n",
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"print(power(2,5))"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.3\n",
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"def power(x,n):\n",
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" \"recursian trace method\"\n",
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" if n==0:\n",
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" return 1\n",
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" else:\n",
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" partial = power(x,n//2)\n",
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" result = partial*partial\n",
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" if n%2==1:\n",
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" result*=x\n",
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" return result\n",
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"\n",
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"\"\"\"\n",
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"power(2,10) --> power(2,5)*power(2,5) = 32*32 = 1024\n",
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" power(2,5) --> power(2,2)*power(2,2)*2 = 4*4*2 = 32\n",
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" power(2,2) --> power(2,1)*power(2,1) = 2*2 = 4\n",
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" power(2,1) --> power(2,0)*power(2,0) = 1*1\n",
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" power(2,0) --> 1\n",
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"\"\"\""
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.4\n",
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"def reverse(S, start, stop):\n",
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" if start < stop - 1:\n",
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" S[start], S[stop-1] = S[stop-1], S[start]\n",
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" reverse(S, start+1, stop-1)\n",
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"\n",
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"\"\"\"\n",
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"S=[0,1,2,3,4,5,6,7]\n",
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"start,stop = 0,8 -> S[0],S[7] <->\n",
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" start,stop = 1,7 -> S[1],S[6] <->\n",
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" start,stop = 2,6 -> S[2],S[5] <->\n",
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" start,stop = 3,5 -> S[3],S[4] <->\n",
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" start,stop = 4,4 -> S[4],S[3] skip, and the rest\n",
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"\"\"\""
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.5 -- skip"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.6\n",
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"def HarmonicNum(n):\n",
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" if n==1:\n",
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" return 1\n",
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" else:\n",
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" return 1/n+HarmonicNum(n-1)\n",
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"\n",
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"HarmonicNum(5)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.7, 4.8 skip\n",
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"def string2int(string):\n",
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" n=len(string)\n",
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" if n!=0:\n",
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" return int(string[0])*(10**(n-1)) + string2int(string[1:n])\n",
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" else:\n",
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" return 0\n",
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"\n",
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"a = string2int('12345607')\n",
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"print(a, type(a))"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.9\n",
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"def FindMinMax(egset, index=0):\n",
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" if index==len(egset)-1:\n",
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" minx, maxx = egset[index],egset[index]\n",
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" return minx, maxx\n",
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" else:\n",
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" minx, maxx = FindMinMax(egset,index+1)\n",
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" return min(egset[index], minx), max(egset[index], maxx)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"s1=[1,3,5,6,3,6,-3,20,4,3]\n",
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"s2=[9,3,4,2,5,6,8,34,-40,32]\n",
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"print(FindMinMax(s1))\n",
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"print(FindMinMax(s2))"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.10\n",
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"def log2int(n):\n",
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" assert n>0\n",
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" if n<2:\n",
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" return 0\n",
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" else:\n",
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" return 1+log2int(n//2)\n",
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"\n",
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"log2int(16)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.11\n",
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"def uniquecheck(S, index=0):\n",
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" if index==len(S)-1:\n",
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" return True\n",
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" else:\n",
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" unique=True\n",
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" for i in range(index+1, len(S)):\n",
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" if S[index]==S[i]:\n",
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" unique=False\n",
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" return unique and uniquecheck(S,index+1)\n",
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"\n",
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"for S in [[1,2,3,4,5,6], \n",
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" [3,4,5,2,3,4,6,7],\n",
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" [234,654,32,543,652]\n",
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" ]:\n",
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" print(uniquecheck(S))"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# 4.12, 4.13 skipped\n",
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"def product(m,n):\n",
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" if n==0:\n",
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" return 0\n",
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" else:\n",
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" return m + product(m,n-1)\n",
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"\n",
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"product(2,6)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 11,
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"metadata": {},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"1\n",
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"2\n",
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"3\n",
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"4\n"
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]
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}
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],
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"source": [
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"s=[1,2,3,4]\n",
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"for i in range(len(s)):\n",
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" print(s[i])"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 25,
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"metadata": {},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"[2, 3, 4]\n",
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"[1, 3, 4]\n",
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"[1, 2, 4]\n",
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"[1, 2, 3]\n",
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"1\n",
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"[3, 4]\n",
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"[2, 4]\n",
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"[2, 3]\n",
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"3\n",
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"[4]\n",
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"[2]\n"
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]
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},
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{
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"ename": "IndexError",
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"evalue": "pop index out of range",
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"output_type": "error",
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"traceback": [
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"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
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"\u001b[0;31mIndexError\u001b[0m Traceback (most recent call last)",
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"\u001b[1;32m/home/gvh/Desktop/data structure & algo practise/exe4.ipynb Cell 14\u001b[0m in \u001b[0;36m<cell line: 30>\u001b[0;34m()\u001b[0m\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=25'>26</a>\u001b[0m subset(setcopy,n\u001b[39m+\u001b[39m\u001b[39m1\u001b[39m)\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=26'>27</a>\u001b[0m \u001b[39melse\u001b[39;00m: \u001b[39mreturn\u001b[39;00m S\n\u001b[0;32m---> <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=29'>30</a>\u001b[0m subset([\u001b[39m1\u001b[39;49m,\u001b[39m2\u001b[39;49m,\u001b[39m3\u001b[39;49m,\u001b[39m4\u001b[39;49m])\n",
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"\u001b[1;32m/home/gvh/Desktop/data structure & algo practise/exe4.ipynb Cell 14\u001b[0m in \u001b[0;36msubset\u001b[0;34m(S, n)\u001b[0m\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=23'>24</a>\u001b[0m \u001b[39m# subset(setcopy2,n+1)\u001b[39;00m\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=24'>25</a>\u001b[0m \u001b[39mprint\u001b[39m(setcopy\u001b[39m.\u001b[39mpop(n))\n\u001b[0;32m---> <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=25'>26</a>\u001b[0m subset(setcopy,n\u001b[39m+\u001b[39;49m\u001b[39m1\u001b[39;49m)\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=26'>27</a>\u001b[0m \u001b[39melse\u001b[39;00m: \u001b[39mreturn\u001b[39;00m S\n",
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"\u001b[1;32m/home/gvh/Desktop/data structure & algo practise/exe4.ipynb Cell 14\u001b[0m in \u001b[0;36msubset\u001b[0;34m(S, n)\u001b[0m\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=23'>24</a>\u001b[0m \u001b[39m# subset(setcopy2,n+1)\u001b[39;00m\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=24'>25</a>\u001b[0m \u001b[39mprint\u001b[39m(setcopy\u001b[39m.\u001b[39mpop(n))\n\u001b[0;32m---> <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=25'>26</a>\u001b[0m subset(setcopy,n\u001b[39m+\u001b[39;49m\u001b[39m1\u001b[39;49m)\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=26'>27</a>\u001b[0m \u001b[39melse\u001b[39;00m: \u001b[39mreturn\u001b[39;00m S\n",
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"\u001b[1;32m/home/gvh/Desktop/data structure & algo practise/exe4.ipynb Cell 14\u001b[0m in \u001b[0;36msubset\u001b[0;34m(S, n)\u001b[0m\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=22'>23</a>\u001b[0m \u001b[39mprint\u001b[39m(setcopy2)\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=23'>24</a>\u001b[0m \u001b[39m# subset(setcopy2,n+1)\u001b[39;00m\n\u001b[0;32m---> <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=24'>25</a>\u001b[0m \u001b[39mprint\u001b[39m(setcopy\u001b[39m.\u001b[39;49mpop(n))\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=25'>26</a>\u001b[0m subset(setcopy,n\u001b[39m+\u001b[39m\u001b[39m1\u001b[39m)\n\u001b[1;32m <a href='vscode-notebook-cell:/home/gvh/Desktop/data%20structure%20%26%20algo%20practise/exe4.ipynb#X15sZmlsZQ%3D%3D?line=26'>27</a>\u001b[0m \u001b[39melse\u001b[39;00m: \u001b[39mreturn\u001b[39;00m S\n",
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"\u001b[0;31mIndexError\u001b[0m: pop index out of range"
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]
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}
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],
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"source": [
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"# 4.14 skipped temporarily\n",
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"# 4.15\n",
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"def subset(S,n=0):\n",
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" setcopy=S.copy()\n",
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" if len(setcopy)>1:\n",
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" for i in range(len(setcopy)):\n",
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" setcopy2=setcopy.copy()\n",
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" # print(f'minus n={n},i={i}')\n",
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" setcopy2.pop(i)\n",
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" # return setcopy2\n",
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" print(setcopy2)\n",
297+
" # subset(setcopy2,n+1)\n",
298+
" print(setcopy.pop(n))\n",
299+
" subset(setcopy,n+1)\n",
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" else: return S\n",
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" \n",
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"\n",
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"subset([1,2,3,4])"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": []
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 3.9.12 ('deepcv')",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.9.12"
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},
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"orig_nbformat": 4,
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"vscode": {
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"interpreter": {
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"hash": "38e3adfb29cde9206c861f814c9fa42a1353f77e60ebe68d31b54d2673048b17"
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}
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"nbformat": 4,
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"nbformat_minor": 2
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}

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