Solution of problems 117, 124, 127, 130, 140, 146, 150, 153, 162, 190, 212, 218, 239

Author: Garvit244

1-100q/10.py

@@ -21,6 +21,10 @@ def isMatch(self, s, p):
         dp = [[False for _ in range(len(p) + 1)] for _ in range(len(s) + 1)]
         dp[0][0] = True
 
+ 		for index in range(1, len(dp[0])):
+            if p[index-1] == '*':
+                dp[0][index] = dp[0][index - 2]
+                
         for index_i in range(1, len(dp)):
         	for index_j in range(1, len(dp[0])):
         		if s[index_i - 1] == p[index_j - 1] or p[index_j - 1] == '.':

1-100q/8.py

@@ -0,0 +1,38 @@
+class Solution:
+    def myAtoi(self, str):
+        """
+        :type str: str
+        :rtype: int
+        """
+        str = str.strip()
+        number = ""
+        
+        
+        for x in str:
+            if x.isalpha() and number == "":
+                return 0
+            elif x.isalpha():
+                break
+            elif x == ".":
+                break
+            elif x == " ":
+                break
+            elif (x == "+" or x == "-") and number == "":
+                number = number + x
+            elif (x == "+" or x == "-") and number != "":
+                break
+            elif (x == "+" or x == "-") and (number[-1] == "+" or number[-1] == "-"):
+                return 0
+            elif (x == "+" or x == "-") and ("+" in number or "-" in number):
+                break
+            elif x.isdigit():
+                number = number + x
+        if number == "" or number == "+" or number == "-":
+            return 0
+        else:
+            if int(number) > ((2**31)-1):
+                return (2**31)-1
+            elif int(number) < -(2**31):
+                return -(2**31)
+            else:
+                return int(number)

100-200q/117.py

@@ -55,3 +55,50 @@ def connect(self, root):
     				queue.append(front.right)
     		elif queue:
     			queue.append(None)
+
+
+# Definition for binary tree with next pointer.
+# class TreeLinkNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+#         self.next = None
+
+class Solution:
+    # @param root, a tree link node
+    # @return nothing
+    def connect(self, root):
+    	if not root:
+    		return None
+
+    	root.next = None
+
+    	while root:
+    		temp = root
+    		while temp:
+    			if temp.left:
+    				if temp.right:
+    					temp.left.next = temp.right
+    				else:
+    					temp.left.next = self.getNext(temp)
+    			if temp.right:
+    				temp.right.next = self.getNext(temp)
+
+    			temp = temp.next
+    		if root.left:
+    			root = root.left
+    		elif root.right:
+    			root = root.right
+    		else:
+    			root = self.getNext(root)
+
+    def getNext(self, node):
+    	node = node.next
+    	while node:
+    		if node.left:
+    			return node.left
+    		if node.right:
+    			return node.right
+    		node = node.next
+    	return None

100-200q/124.py

@@ -0,0 +1,57 @@
+'''
+	Given a non-empty binary tree, find the maximum path sum.
+
+	For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The path must contain at least one node and does not need to go through the root.
+
+	Example 1:
+
+	Input: [1,2,3]
+
+	       1
+	      / \
+	     2   3
+
+	Output: 6
+	Example 2:
+
+	Input: [-10,9,20,null,null,15,7]
+
+	   -10
+	   / \
+	  9  20
+	    /  \
+	   15   7
+
+	Output: 42
+'''
+
+# Definition for a binary tree node.
+# class TreeNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution(object):
+    def maxPathSum(self, root):
+        """
+        :type root: TreeNode
+        :rtype: int
+        """
+        self.result = float('-inf')
+        self.dfs(root)
+        return self.result
+
+    def dfs(self, root):
+    	if not root:
+    		return 0
+
+    	l = self.dfs(root.left)
+    	r = self.dfs(root.right)
+
+    	max_one_end = max(max(l, r)+root.val, root.val)
+    	max_path = max(max_one_end, l+r+root.val)
+    	self.result = max(self.result, max_path)
+    	return max_one_end
+
+

100-200q/127.py

@@ -39,7 +39,7 @@ def ladderLength(self, beginWord, endWord, wordList):
         			d[s].append(word)
         		else:
         			d[s] = [word]
-
+        print d
         queue, visited = [], set()
         queue.append((beginWord, 1))
         while queue:
@@ -60,3 +60,5 @@ def ladderLength(self, beginWord, endWord, wordList):
 	        				if neigh not in visited:
 	        					queue.append((neigh, steps+1))
         return 0
+
+Solution().ladderLength("hit", "cog", ["hot","dot","dog","lot","log","cog"]  )

100-200q/130.py

@@ -23,4 +23,36 @@ def solve(self, board):
         :type board: List[List[str]]
         :rtype: void Do not return anything, modify board in-place instead.
         """
-        
+        if len(board) == 0:
+            return
+        for row in range(len(board)):
+            if board[row][0] == 'O':
+                self.merge(board, row, 0)
+            if board[row][len(board[0])-1] == 'O':
+                self.merge(board, row, len(board[0])-1)
+        
+        for col in range(len(board[0])):
+            if board[0][col] == 'O':
+                self.merge(board, 0, col)
+            
+            if board[len(board)-1][col] == 'O':
+                self.merge(board, len(board)-1, col)
+                
+        for row in range(len(board)):
+            for col in range(len(board[0])):
+                if board[row][col] == 'O':
+                    board[row][col] = 'X'
+                elif board[row][col] == '#':
+                    board[row][col] = 'O'
+                    
+    def merge(self, board, row, col):
+        if row < 0 or col < 0 or row >= len(board) or col >= len(board[0]):
+            return 
+        if board[row][col] != 'O':
+            return 
+        
+        board[row][col] = '#'
+        self.merge(board, row+1, col)
+        self.merge(board, row, col-1)
+        self.merge(board, row, col+1)
+        self.merge(board, row-1, col)  

100-200q/140.py

@@ -0,0 +1,30 @@
+class Solution(object):
+    def wordBreak(self, s, wordDict):
+        """
+        :type s: str
+        :type wordDict: List[str]
+        :rtype: List[str]
+        """
+        self.result = []
+        self.dfs(s, wordDict, '')
+        return self.result
+
+    def dfs(self, s, wordDict, currStr):
+    	if self.check(s, wordDict):
+    		if len(s) == 0:
+    			self.result.append(currStr[1:])
+    		for i in range(1, len(s)+1):
+    			if s[:i] in wordDict:
+    				self.dfs(s[i:], wordDict, currStr + ' ' + s[:i])
+
+    def check(self, s, wordDict):
+    	dp = [False for _ in range(len(s)+1)]
+    	dp[0] = True
+
+    	for i in range(len(s)):
+    		for j in range(i, -1, -1):
+    			if dp[j] and s[j:i+1] in wordDict:
+    				dp[i+1] = True
+    				break
+
+    	return dp[len(s)]

100-200q/146.py

@@ -0,0 +1,97 @@
+'''
+	Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and put.
+
+	get(key) - Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1.
+	put(key, value) - Set or insert the value if the key is not already present. When the cache reached its capacity, it should invalidate the least recently used item before inserting a new item.
+
+	Follow up:
+	Could you do both operations in O(1) time complexity?
+
+	Example:
+
+	LRUCache cache = new LRUCache( 2 /* capacity */ );
+
+	cache.put(1, 1);
+	cache.put(2, 2);
+	cache.get(1);       // returns 1
+	cache.put(3, 3);    // evicts key 2
+	cache.get(2);       // returns -1 (not found)
+	cache.put(4, 4);    // evicts key 1
+	cache.get(1);       // returns -1 (not found)
+	cache.get(3);       // returns 3
+	cache.get(4);       // returns 4
+
+'''
+
+class Node(object):
+    def __init__(self, key, value):
+        self.key = key
+        self.value = value
+        self.next = None
+        self.prev = None
+        
+class LRUCache(object):
+
+    def __init__(self, capacity):
+        """
+        :type capacity: int
+        """
+        self.capacity = capacity
+        self.mapping = dict()
+        self.head = Node(0, 0)
+        self.tail = Node(0, 0)
+        self.head.next = self.tail
+        self.tail.prev = self.head
+        
+
+    def get(self, key):
+        """
+        :type key: int
+        :rtype: int
+        """
+        if key in self.mapping:
+            node = self.mapping[key]
+            self.remove(node)
+            self.add(node)
+            return node.value
+        return -1
+        
+
+    def put(self, key, value):
+        """
+        :type key: int
+        :type value: int
+        :rtype: void
+        """
+        
+        if key in self.mapping:
+            self.remove(self.mapping[key])
+            
+        node = Node(key, value)
+        if len(self.mapping) >= self.capacity:
+            next_head = self.head.next
+            self.remove(next_head)
+            del self.mapping[next_head.key]
+            
+        self.add(node)
+        self.mapping[key] = node
+        
+    def add(self, node):
+        tail = self.tail.prev
+        tail.next = node
+        self.tail.prev = node
+        node.prev = tail
+        node.next = self.tail
+        
+    def remove(self, node):
+        prev_node = node.prev
+        prev_node.next = node.next
+        node.next.prev = prev_node
+        
+        
+
+
+# Your LRUCache object will be instantiated and called as such:
+# obj = LRUCache(capacity)
+# param_1 = obj.get(key)
+# obj.put(key,value)