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Givennpairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, givenn= 3, a solution set is:"((()))... 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 n... 阅读全文
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1 /** 2 * Definition for singly-linked list. 3 * struct ListNode { 4 * int val; 5 * ListNode *next; 6 * ListNode(int x) : val(... 阅读全文
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Follow up for "Remove Duplicates":What if duplicates are allowed at mosttwice?For example,Given sorted array A =[1,1,1,2,2,3],Your function should ret... 阅读全文
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Given amxngrid filled with non-negative numbers, find a path from top left to bottom right whichminimizesthe sum of all numbers along its path.Note:Yo... 阅读全文
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题目：Reverse a singly linked list.解题:反转单链表，不再多介绍了.如果会“先条件->定参数->确定不变式->验证后条件”的思维方法，一定会bug free. 1 /** 2 * Definition for singly-linked list. 3 * struc... 阅读全文
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未完成，还可以找到更好的解 1 /** 2 * Definition for singly-linked list. 3 * struct ListNode { 4 * int val; 5 * ListNode *next; 6 * ListNode(int x)... 阅读全文