题目在这里: https://leetcode.com/problems/two-sum/ [标签]Array; Hash Table [个人分析] 这个题目,我感觉也可以算是空间换时间的例子.如果是O(n^2)的那种思路,就是对于一个数字,去扫剩下的所有数字,看有没有能够加起来和为target的组合.但是如果加入一个哈希表,我们扫过的数字都可以记录下来. 我用的是 (target - number) 作为key, 用number在nums中的 index 作为 value, 遇到一个新的数字n…

Given an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that…

索引 思路1:暴力搜索 思路2:聪明一点的搜索 思路3:利用HashMap巧解 问题描述:https://leetcode.com/problems/two-sum/ 思路1:暴力搜索 一个很自然的想法就是暴力搜索了.根据排列组合原理,列举Cn取2对数字,逐对进行判断,效率是O(n^2-1/2n),代码如下: var twoSum = function(nums, target) { for (let i = 0; i != nums.length; ++i) { for (let j = i…

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 the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 return true…

Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. The same repeated number may be chosen from C unlimited number of times. Note: All numbers (including target) will…

注意点: HashMap<Integer, Integer> return new int[]{}; 3 2 4 target:6 return null; public int[] twoSum(int[] nums, int target) { HashMap<Integer, Integer> m = new HashMap<>(); for(int i = 0; i < nums.length; ++i){ if(m.containsKey(target…

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Ensure that numbers within the set are sorted in ascending order. Example 1…

LeetCode 算法题解 js 版 (001 Two Sum) 两数之和 https://leetcode.com/problems/two-sum/submissions/ https://leetcode-cn.com/problems/two-sum/submissions/ 1. 暴力解法 Time complexity: O(n**2) Space complexity: O(n) "use strict"; /** * @author xgqfrms * @descrip…

题目: Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. 翻译: 给定一组整数,两个数字的返回索引,它们的和会等于一个特定…

题目: Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. 翻译: 给定一组整数,两个数字的返回索引,它们的和会等于一个特定…