Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution. Example: Given array nu…

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution. For example, given array S = {- -},…

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution. For example, given array S = {-1 2…

一.模板以及题目分类 1.头尾指针向中间逼近 ; ; while (pos1<pos2) { //判断条件 //pos更改条件 if (nums[pos1]<nums[pos2]) pos1++; else pos2--; } 经典的找和的问题都可以从这种思路下手,2数之和,3数之和,还注意要区分是寻找值还是索引(寻找索引则不能排序),是否允许有重复,不允许重复时要怎样避开重复值. 避开重复值的方法,当然,在3sum和4sum中的ij要稍微做修改 && nums[i] == n…

第一题是Two Sum 同样是用哈希表来做,需要注意的是在查打gap是要排除本身.比如target为4,有一个值为2,gap同样为2. vector<int> twoSum(vector<int> &num, int target) { unordered_map<int, int> mapping; vector<int> result; ; i < num.size(); i++) mapping[num[i]] = i; ; i <…

Two Sum 題目連結 官網題目說明: 解法: 從給定的一組值內找出第一組兩數相加剛好等於給定的目標值,暴力解很簡單(只會這樣= =),兩個迴圈,只要找到相加的值就跳出. /// <summary> /// 暴力解O(n) /// </summary> /// <param name="nums"></param> /// <param name="target"></param> /// &…

题目链接:Path Sum II | LeetCode OJ 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],…

题目链接:Path Sum | LeetCode OJ 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…

Sum of Consecutive Prime Numbers Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 20050   Accepted: 10989 Description Some positive integers can be represented by a sum of one or more consecutive prime numbers. How many such representatio…

题目链接:Sum 嗯--不要在意--我发这篇博客只是为了保存一下杜教筛的板子的-- 你说你不会杜教筛?有一篇博客写的很好,看完应该就会了-- 这道题就是杜教筛板子题,也没什么好讲的-- 下面贴代码(不知道为什么我的常数就是大): #include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<cmath> #define File(s) freo…