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Invert a binary tree. Example: Input: Output: code 阅读全文
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Given a non-negative integer c, your task is to decide whether there're two integers a and b such that a2 + b2 = c. Example 1: Example 2: 题意： 给定非负整数c， 阅读全文
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A group of two or more people wants to meet and minimize the total travel distance. You are given a 2D grid of values 0 or 1, where each 1 marks the h 阅读全文
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Write a program that outputs the string representation of numbers from 1 to n. But for multiples of three it should output “Fizz” instead of the numbe 阅读全文
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Given a linked list, return the node where the cycle begins. If there is no cycle, return null. To represent a cycle in the given linked list, we use 阅读全文
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You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k. Define a pair (u,v) which consists of one element from th 阅读全文
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Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand. (i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]). F 阅读全文
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Given two sequences pushed and popped with distinct values, return true if and only if this could have been the result of a sequence of push and pop o 阅读全文
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如图 阅读全文
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Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjac 阅读全文