#include <iostream> #include <cstdio> #include <cstring> using namespace std; char s[100],*dic[]={"zero","one","two","three","four","five","six","seven",&quo…

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…

BZOJ_4653_[Noi2016]区间_线段树+离散化+双指针 Description 在数轴上有 n个闭区间 [l1,r1],[l2,r2],...,[ln,rn].现在要从中选出 m 个区间,使得这 m个区间共同包含至少一个位置.换句话说,就是使得存在一个 x,使得对于每一个被选中的区间 [li,ri],都有 li≤x≤ri. 对于一个合法的选取方案,它的花费为被选中的最长区间长度减去被选中的最短区间长度.区间 [li,ri] 的长度定义为 ri−li,即等于它的右端点的值减去左端点的值…

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 target, where index1 m…

Given a binary array, find the maximum number of consecutive 1s in this array. Example 1: Input: [1,1,0,1,1,1] Output: 3 Explanation: The first two digits or the last three digits are consecutive 1s. The maximum number of consecutive 1s is 3. Note: T…

Given an array nums and a value val, remove all instances of that value in-place and return the new length. Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory. The order of ele…

Write a function that reverses a string. The input string is given as an array of characters char[]. Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory. You may assume all the…

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 an integer pos which represents the position (0-indexed) in the linked list where tail connects to.…

Given a linked list, remove the n-th node from the end of list and return its head. Example: Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, the linked list becomes 1->2->3->5. Note: Given n w…

Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: begin to intersect at node c1. Example 1: Input: intersectVal = 8, listA = [4,1,8,4,5], listB = [5,0,1,8,4,5],…

Given a linked list, determine if it has a cycle in it. To represent a cycle in the given linked list, we use an integer pos which represents the position (0-indexed) in the linked list where tail connects to. If pos is -1, then there is no cycle in…

pro: 给出圆周上的若干个点,已知点与点之间的弧长,其值均为正整数,并依圆周顺序排列. 请找出这些点中有没有可以围成矩形的,并希望在最短时间内找出所有不重复矩形. N<20; sol:很可能被数据量误导,以为是个难题. 以为圆内接矩形的对角线经过圆中间,所以我们枚举对角线,然后组合数即可.  求过圆心的对角线可以暴力或者双指针. #include<bits/stdc++.h> #define ll long long #define rep(i,a,b) for(int i=a;i&l…

题目描述 给定一个长度为n的序列,你有一次机会选中一段连续的长度不超过d的区间,将里面所有数字全部修改为0.请找到最长的一段连续区间,使得该区间内所有数字之和不超过p. 输入 第一行包含三个整数n,p,d(1<=d<=n<=2000000,0<=p<=10^16).第二行包含n个正整数,依次表示序列中每个数w[i](1<=w[i]<=10^9). 输出 包含一行一个正整数,即修改后能找到的最长的符合条件的区间的长度. 样例输入 9 7 2 3 4 1 9 4 1…

http://codeforces.com/problemset/problem/912/E 题意·n个质数,问因子中只包含这其中几个质数的第k大的数是多少 最显然的想法是暴力搜预处理出所有的小于1e18的值,排序后直接输出,但是n的范围是16,仔细一想发现事实并不可行,不论是时间还是空间都不允许. 本题的难点在于考虑到用折半将其分成两个集合,预处理出每个集合内所有可能的数,由于一个集合最多只有8个,这是一个允许爆搜的范围,与处理完了之后二分出答案即可,check函数里需要用到双指针的技巧来查找…

比赛的时候想着用单调队列做... 打完发现其实就是个双指针 /* 构造双指针解决即可 */ #include<iostream> #include<cstring> #include<cstdio> #include<algorithm> using namespace std; #define maxn 200005 struct sd{int ans,a,id;}x[maxn]; bool cmp1(sd a,sd b){return a.a<b.…

大意: 给定序列, 求多少个区间积被k整除. 整除信息满足单调性, 显然双指针. 具体实现只需要考虑k的素数向量, 对每一维维护个指针即可. 这题看了下cf其他人的做法, 发现可以直接暴力, 若当前的前缀积模k为0, 暴力向前求出第一个后缀积为0的位置即可, 复杂度是$O(n)$的并且相当好写. #include <iostream> #include <algorithm> #include <cstdio> #include <math.h> #incl…

大意: n*n棋盘, n个点有怪兽, 求有多少边长为k的正方形内恰好有k只怪兽, 输出k=1,...,n时的答案和. 等价于给定n排列, 对于任意一个长为$k$的区间, 若最大值最小值的差恰好为k, 则产生1贡献, 求贡献和.考虑分治, 问题就转化为如何$O(n)$求出跨越$mid$的贡献, 可以讨论最大值最小值的位置, 双指针求出. #include <iostream> #include <algorithm> #include <cstdio> #define R…

Problem Description We define the distance of two strings A and B with same length n isdisA,B=∑i=0n−1|Ai−Bn−1−i|The difference between the two characters is defined as the difference in ASCII.You should find the maximum length of two non-overlapping…

Little Sub loves math very much, and has just come up with an interesting problem when he is working on his geometry homework. It is very kind of him to share this problem with you. Please solve it with your coding and math skills. Little Sub says th…

传送门 后缀数组经典题目. 我们先把所有的字符串都接在一起. 然后求出hththt数组和sasasa数组. 然后对于sasasa数组跑双指针统计答案. 如果双指针包括进去的属于不同字符串的数量达到了题目给出的限制我们就更新答案并不断右移左指针. 如果没有达到限制就一直右移右指针. 代码: #include<iostream> #include<cstdio> #include<cstring> #include<vector> #include<cst…

https://codeforces.com/contest/1133/problem/E 题意 给你n个数(n<=5000),你需要对其挑选并进行分组,总组数不能超过k(k<=5000),每组数字差距不超过5,问最多能挑出多少数字 题解 先排序,在进行dp,定义dp[i][j]为前i个数分成j组的最大值 两个转移方向 不选 dp[i-1][j] -> dp[i][j] 和前面的分组 dp[lt[i]-1][j-1] -> dp[i][j] 怎么确定i前面的哪个点是最大的? 选择能…

https://codeforces.com/contest/1121/problem/D 题意 给你一个m(<=5e5)个数的序列,选择删除某些数,使得剩下的数按每组k个数以此分成n组(n*k<=m),存在只要一组满足和目标集合s(|s|<=k)匹配(即集合中存在的数,组内一定存在) 题解 重点:找出至少一组满足要求的数 假设[l,r]内满足要求,还需要满足:\((l-1)/k*k+(m-r)/k*k>=k*(n-1)\),可以用双指针,对于每个l可以处理出最小的r满足要求 这样…

https://codeforces.com/contest/1060/problem/C 题意 给两个数组,a数组有n个元素,b数组有m个元素,两个数组元素互相相乘形成n*m的矩阵,找一个子矩阵,元素和<=x,子矩阵的面积尽量大,求这个子矩阵的面积大小 思路 一开始往二维前缀和+暴力+查询之类想了,没观察规律,复杂度怎么想都不对 规律其实就是 子矩阵的和等于两个数组的连续子序列和相乘,面积大小等于子序列长度相乘 即要在两个数组中找出两个连续的子序列,保证他们的和相乘<=x的情况下,长度的乘积…