#leetcode刷题之路45-跳跃游戏 II

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 5 / 4 8 / / 11 13 4 / \ / 7 2 5 1 return [ [5,4,11,2], [5,8,4,5] ] 给定一个二叉树和数字sum,输出二叉树中从根节点到

Given an array of integers, every element appears three times except for one. Find that single one. 给定一个包含n个整数的数组,除了一个数出现一次外所有的整数均出现三次,找出这个只出现一次的整数. 思路,根据数组构成的特点可知,数组中所有数的某一位上1的个数总和为3*n或者3*n+1. 当只出现一次的整数该位为0时,总和为3*n,当只出现一次的整数该位为1时,总和为3*n+1. 因此我们可以计算数

给定一个数组 candidates 和一个目标数 target ,找出 candidates 中所有可以使数字和为 target 的组合.candidates 中的每个数字在每个组合中只能使用一次.说明:所有数字(包括目标数)都是正整数.解集不能包含重复的组合. 示例 1:输入: candidates = [10,1,2,7,6,1,5], target = 8,所求解集为:[ [1, 7], [1, 2, 5], [2, 6], [1, 1, 6]] 示例 2:输入: candidates =

Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between). For example: Given binary tree {3,9,20,#,#,15,7}, 3 / 9 20 / 15 7 return its zig

Given inorder and postorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. 给出二叉树的中序遍历和后序遍历结果,恢复出二叉树. 后序遍历序列的最后一个元素值是二叉树的根节点的值,查找该元素在中序遍历序列中的位置mid,根据中序遍历和后序遍历性质,有: 位置mid以前的序列部分为二叉树根节点左子树中

You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? 一个台阶总共有n级,如果一次可以跳1级,也可以跳2级,求总共有多少总跳法. 分析: 一次最多只能跳两级,那么对于第n级(n>=2)台阶,显然只能从第n-1级跳一级到达或

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. 将k个有序链表合并成一个有序链表. 思路,之前做过两个有序链表的合并操作,对于k个链表,我们最先想到的就是能不能转化为我们熟悉的两个链表的合并,可以我们先将k个链表分为两部分,先对这两部分完成链表的有序合并操作,再对合并得到的两个链表进行合并,这是一个递归性质的描述,采用递归很容易实现这个程序,和数组

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume no duplicates in the array. Here are few examples. [1,3,5,6], 5 → 2 [1,3,5,6], 2

The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other. Given an integer n, return all distinct solutions to the n-queens puzzle. Each solution contains a distinct board configuration of