2020-02-11

Author: JiayangWu

1342.将数字变成0的操作次数/1342-将数字变成0的操作次数.py

@@ -0,0 +1,14 @@
+class Solution(object):
+    def numberOfSteps (self, num):
+        """
+        :type num: int
+        :rtype: int
+        """
+        cnt = 0
+        while num:
+            if num % 2:
+                num -= 1
+            else:
+                num  >>= 1
+            cnt += 1
+        return cnt

1343.大小为K且平均值大于等于阈值的子数组数目/1343-大小为K且平均值大于等于阈值的子数组数目.py

@@ -0,0 +1,21 @@
+class Solution(object):
+    def numOfSubarrays(self, arr, k, threshold):
+        """
+        :type arr: List[int]
+        :type k: int
+        :type threshold: int
+        :rtype: int
+        """
+        res = 0
+        target_sum = k * threshold
+        subs = 0
+        for i in range(0, k):
+            subs += arr[i]
+        
+        for i in range(0, len(arr) - k + 1):
+            if i:
+                subs = subs - arr[i - 1] + arr[i + k - 1]
+            if subs >= target_sum:
+                res += 1
+                
+        return res

1345.跳跃游戏IV/1345-跳跃游戏IV.py

@@ -0,0 +1,25 @@
+class Solution(object):
+    def minJumps(self, arr):
+        """
+        :type arr: List[int]
+        :rtype: int
+        """
+        from collections import defaultdict, deque
+        dic = defaultdict(list)
+        for i, x in enumerate(arr):
+            if (i and arr[i] != arr[i - 1]) or (i < len(arr) - 1 and arr[i] != arr[i + 1]):
+                dic[x].append(i)
+
+        queue = deque([(0, 0)]) #pos, step 
+        visited = set([0])
+
+        while queue:
+            pos, step = queue.popleft() 
+
+            if pos == len(arr) - 1:
+                return step
+
+            for p in [pos - 1, pos + 1] + dic[arr[pos]]:
+                if 0 <= p < len(arr) and p not in visited:
+                    queue.append((p, step + 1))
+                    visited.add(p)