题目链接:http://www.51nod.com/onlineJudge/questionCode.html#!problemId=1267 题意:中文题诶- 思路:双指针 求a+b+c+d=0,令a+b=e, c+d=f,即e+f=0: 所以可以先给所有数两两求和,并记录其下标,再根据和的大小排序. 再用双指针扫描即可. 代码: #include <iostream> #include <stdio.h> #include <algorithm> #define M…

题意:判断能否从序列中找出4个数的和为0. 解题关键:n^2预处理任意两个数的和,sort一下,双指针进行判定. 此解法尚存在一个问题,就是左右枚举的时候如果相同的有许多的时候该左边移动还是右边移动 #include<bits/stdc++.h> using namespace std; typedef long long ll; ]; struct node{ int x,y,sum; }arr[]; bool cmp(node &a,node &b){ return a.s…

一. 题目 1. Two Sum II Given an array of integers that is already sorted in ascending order, 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 ta…

一. 题目 1. Two SumTotal Accepted: 241484 Total Submissions: 1005339 Difficulty: Easy 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 solutio…

Leetcode解题思想总结篇:双指针 1概念 双指针:快慢指针. 快指针在每一步走的步长要比慢指针一步走的步长要多.快指针通常的步速是慢指针的2倍. 在循环中的指针移动通常为: faster = faster.next.next; slower = slower.next; 2 应用 2.1. 用来判断链表是否有环以及寻找环入口 Linked List Cycle Linked List Cycle II 是否有环:快慢指针思想,注意循环条件:(fast != null) && (fas…

题意很简单,就是寻找一个字符串中连续的最长包含不同字母的子串. 其实用最朴素的方法,从当前字符开始寻找,找到以当前字符开头的最长子串.这个方法猛一看是个n方的算法,但是要注意到由于字符数目的限制,其实这是个O(Cn)的算法,最长也不过是C长度.所以我觉得普通方法应该是能过的. 于是写了一个,字符数目最大也不超过256所以代码如下: class Solution { public: int lengthOfLongestSubstring(string s) { ; ;i<s.length();i…

题目链接 给n个数, 找出三个数相加结果为0的所有的组, 不可重复. 用双指针的思想,O(n^2)暴力的找, 注意判重复. class Solution { public: vector<vector<int>> threeSum(vector<int>& nums) { int sz = nums.size(); vector <vector<int> > ans; vector <int> tmp; sort(nums.b…

题目链接:hdu_5806_NanoApe Loves Sequence Ⅱ 题意: 给你一段数,问你有多少个区间满足第K大的数不小于m 题解: 直接双指针加一下区间就行 #include<cstdio> #include<algorithm> #define F(i,a,b) for(int i=a;i<=b;i++) using namespace std; typedef long long ll; ; int t,n,k,m; int a[N]; int main()…

BZOJ_2679_[Usaco2012 Open]Balanced Cow Subsets _meet in middle+双指针 Description Farmer John's owns N cows (2 <= N <= 20), where cow i produces M(i) units of milk each day (1 <= M(i) <= 100,000,000). FJ wants to streamline the process of milking…

BZOJ_3048_[Usaco2013 Jan]Cow Lineup _双指针 Description Farmer John's N cows (1 <= N <= 100,000) are lined up in a row. Each cow is identified by an integer "breed ID" in the range 0...1,000,000,000; the breed ID of the ith cow in the lineup…