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137. Single Number II Given an array of integers, every element appears three times except for one. Find that single one. Note:Your algorithm should h 阅读全文
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136. Single Number Given an array of integers, every element appears twice except for one. Find that single one. Note:Your algorithm should have a lin 阅读全文
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125. Valid Palindrome Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man 阅读全文
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121. Best Time to Buy and Sell Stock Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitte 阅读全文
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119. Pascal's Triangle II Given an index k, return the kth row of the Pascal's triangle. For example, given k = 3,Return [1,3,3,1]. Note:Could you opt 阅读全文
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118. Pascal's Triangle Given numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5,Return 阅读全文
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112. Path Sum Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals th 阅读全文
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111. Minimum Depth of Binary Tree Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from t 阅读全文
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110. Balanced Binary Tree Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a bin 阅读全文
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107. Binary Tree Level Order Traversal II Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to righ 阅读全文