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Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequ 阅读全文
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Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contains only 阅读全文
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Given n non-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the hist 阅读全文
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位运算： https://www.cnblogs.com/liaopeng/p/8436155.html 0>>1 = 0 (0<<1) + 1 = 1 0<<1 = 0 (0>>1) + 1 = 1 1&1 = 1, 0&1 = 0; Hashmap basic methods: https:// 阅读全文