题意:有一个长度为\(n\)并且所有元素和为\(0\)的序列,你可以使\(a_{i}-1\)并且\(a_{j}+1\),如果\(i<j\),那么这步操作就是免费的,否则需要花费一次操作,问最少操作多少次使得所有元素为\(0\). 题解:首先优先考虑不用花费的情况,如果\(a_{i}>0\),\(a_{j}<0\),且\(i<j\),那么我们可以免费的使这两个或一个元素变为\(0\),这里我们可以倒着遍历,记录负数的和,如果遇到正数就抵消,如果不足以抵消正数,那么该位置剩余的正数值就…

https://codeforces.com/contest/1065 题意 给你a,b,让你找尽量多的自然数,使得他们的和<=a,<=b,用在a和b的自然数不能重复 思路 假如只有一个数a让你去找,问题就很简单了,就是找到一个x,使得x尽量大,且x*(x+1)/2<=a,意味着答案就是1~x 我的思路是从1开始累加,加到一个不能再加的数时,向后退一个数,加上n-sum(1~a[i-1])(ps:a[i+1]为不能再加的数) 错误贪心思想:假如加到不能再加,同样是只能再加一个数了,不如把…

题意:给你一组人\(a\),现在要将这些人进行分组,对于\(i\),只有某一组的人数\(\ge a_{i}\)时,\(i\)才可以加入这个组,问最多能够有多少组,(不必将所有人都选用). 题解:我们将所有\(a_{i}\)相同的用一个桶存一下,然后升序遍历这个桶,假如桶里面的人数\(\ge a_{i}\),那么它们就能够组成一组,之后我们再取余,将剩下的人记录下来,继续遍历后面的桶,如果这些剩余的人数\(\ge a_{i}\),那么它们也可以组成一组,继续遍历下去就行了. 代码: #includ…

Codeforces Round #297 (Div. 2)C. Ilya and Sticks Time Limit: 2 Sec  Memory Limit: 256 MBSubmit: xxx  Solved: 2xx 题目连接 http://codeforces.com/contest/525/problem/C Description In the evening, after the contest Ilya was bored, and he really felt like ma…

A. Permutation Forgery 题目:http://codeforces.com/contest/1405/problem/A 题解:这道题初看有点吓人,一开始居然想到要用全排序,没错我真傻,TLE,之后再想后发现,将数组反过来,两两相加的和和正着的是一样的,因此我们只需将数组倒叙即可. 代码: #include<bits/stdc++.h> //POJ不支持 #define IOS ios::sync_with_stdio(false);cin.tie(0); cout.tie…

比赛链接:https://codeforces.com/contest/1405 A. Permutation Forgery 题意 给出一个大小为 $n$ 的排列 $p$,定义 \begin{equation} F(p)=\mathrm{sort}([p_1+p_2,p_2+p_3,\ldots,p_{n-1}+p_n]) .\nonumber \end{equation} 试找出一个不同于 $p$ 的 $p'$ 满足 $F(p') = F(p)$ . 题解 反转 $p$ 即可. 代码 #in…

A. Array 题目连接: http://www.codeforces.com/contest/300/problem/A Description Vitaly has an array of n distinct integers. Vitaly wants to divide this array into three non-empty sets so as the following conditions hold: The product of all numbers in the…

题目链接: http://codeforces.com/problemset/problem/498/C C. Array and Operations time limit per test1 secondmemory limit per test256 megabytes 问题描述 You have written on a piece of paper an array of n positive integers a[1], a[2], ..., a[n] and m good pair…

传送门:http://codeforces.com/contest/1108/problem/E2 E2. Array and Segments (Hard version) time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output The only difference between easy and hard versions i…

t题目链接:http://codeforces.com/contest/1291/problem/B 思路: 用极端的情况去考虑问题,会变得很简单. 无论是单调递增,单调递减,或者中间高两边低的情况都可以变为三种模型. (1)0,1,2,3,4........n-3,n-2,n-1 (2)n-1,n-2,n-3.....3,2,1,0 (3)0,1,2,3,4,.....n.......4,3,2,1,0 那么,我们只需要查看当前位置是否大于等于极端模型(3)在这个位置的数值,如果当前位置不满足…

You are given an array aa consisting of nn integers. In one move, you can choose two indices 1≤i,j≤n1≤i,j≤n such that i≠ji≠j and set ai:=ajai:=aj . You can perform such moves any number of times (possibly, zero). You can choose different indices in d…

因为只有奇偶之间有操作, 可以看出是二分图, 然后拆质因子, 二分图最大匹配求答案就好啦. #include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk make_pair #define PLL pair<LL, LL> #define PLI pair<LL, int> #define PII pair<int, int> #defin…

题目 题意: 给你n个数,有两种操作,操作1是把第i个位置的数删去, 操作2 是把 a[ j ]= a[ i ]* a[ j ],把a[ i ]删去 .n-1个操作以后,只剩1个数,要使这个数最大 .要你输出这n-1个步骤. 思路: 结构体储存数和位置, 按值排序,然后分类讨论. 1. 负数个数是奇数,无0  .删除最大的一个负数,别的数正常搞定. 2. 负数个数是奇数,有0  .把最大的一个负数给堆积到最后一个0上,删除最后一个0 . 3. 负数个数是偶数,无0  . 不用删,正常处理. 4.…

题目链接 题目大意 给你一颗树,Alice在a点,Bob在b点,Alice最多走da步,Bob最多走db步,两人轮流走路.要你判断经过无数次追赶后,Alice是否可以追上Bob,两人进行的都是最优策略 题目思路 感觉也不特别像一个博弈,但是也不知道该划分到哪里了 这个题目没想象的那么难,首先如果a和b的距离小于da,那么肯定Alice胜,如果2da>=len,len代表树的直径,那么也是Alice胜. 前两个都是显然的. 还有一种如果2*da>=db,这个代表不存在A只差一步追上B的时候,B可…

题意:有\(n\)个数,首先任选一个正整数\(x\),然后在数组中找到两个和为\(x\)的数,然后去掉这两个数,\(x\)更新为两个数中较大的那个.问你最后时候能把所有数都去掉,如果能,输出最初的\(x\)和每次去除的两个数. 题解:首先现将数组排序,我们每次肯定都是要用数组中当前最大的数和其他数进行组合,这很容易证明,假如我们选两个比它小的数,那么更新后的\(x\)一定永远小于最大值,那么它就永远用不掉,那么第一次的\(x\)一定是数组的最大值和某个数的组合,我们可以枚举来处理,然后剩下的过程…

题意:给你\(n\)个数字,用\(k\)种颜色给他们涂色,要求每个数字都要涂,每种颜色都要用,相同的数字不能涂一样的颜色. 题解:用结构体读入每个数字和它的位置,然后用桶记录每个数字出现的次数,判断是否合法,然后对数字进行排序,从\([1,k]\)不断循环的去涂颜色,这样的好处是一定能保证相同数字涂的颜色不同,然后再按位置排序输出即可. 代码: struct misaka{ int val; int id; int col; }e[N]; int n,k; map<int,int> mp; i…

B. Anton and Lines   The teacher gave Anton a large geometry homework, but he didn't do it (as usual) as he participated in a regular round on Codeforces. In the task he was given a set of n lines defined by the equations y = ki·x + bi. It was necess…

地址:http://codeforces.com/problemset/problem/712/C 题目: C. Memory and De-Evolution time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Memory is now interested in the de-evolution of objects, sp…

题目链接:http://codeforces.com/problemset/problem/731/C 题意:有n只袜子,每只都有一个颜色,现在他的妈妈要去出差m天,然后让他每天穿第 L 和第 R 只袜子,他为了让每天穿的袜子都是一个颜色的,他需要把袜子涂色,共有k种颜色,求最少需要涂多少只袜子,才能保证他每天穿的袜子都是一样的. 用并查集把所有联系在一起的袜子放到一个集合中去,然后这些袜子会变成一块一块的,我们在每一块中找一种颜色最多的,然后把当前块中的其他袜子都涂成这种颜色即可,累加即可 #…

A. Vitya in the Countryside time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Every summer Vitya comes to visit his grandmother in the countryside. This summer, he got a huge wart. Every gran…

题目链接: http://codeforces.com/contest/672/problem/C 题意: 公园里有两个人一个垃圾桶和n个瓶子,现在这两个人需要把所有的瓶子扔进垃圾桶,给出人,垃圾桶,瓶子的坐标,问两个人需要走的最短距离和. 题解: 首先必须要有一个人先去检一个瓶子,然后走到垃圾桶,这个可以枚举,接下来就是考虑另一个人是也捡一个瓶子然后走到垃圾桶(这个可以预处理出最优的,和次优的,因为如果最优的那个刚好被第一个人拿走了,那就拿次优的)还是在原地不动,接下去就是固定的了,求剩下的所…

D. Finals in arithmetic 题目连接: http://www.codeforces.com/contest/625/problem/D Description Vitya is studying in the third grade. During the last math lesson all the pupils wrote on arithmetic quiz. Vitya is a clever boy, so he managed to finish all th…

B. Vika and Squares 题目连接: http://www.codeforces.com/contest/610/problem/B Description Vika has n jars with paints of distinct colors. All the jars are numbered from 1 to n and the i-th jar contains ai liters of paint of color i. Vika also has an infi…

C. GukiZ hates Boxes Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/551/problem/C Description Professor GukiZ is concerned about making his way to school, because massive piles of boxes are blocking his way. In total there…

题目链接:http://codeforces.com/contest/675/problem/C 给你n个bank,1~n形成一个环,每个bank有一个值,但是保证所有值的和为0.有一个操作是每个相邻的bank之间可以转钱,让你用最少的操作使每个bank的值为0. 一开始没什么思路,看了一下别人的题解,果然还是还是native... 要是让操作次数变少,首先划分和为0的区间个数要尽量多,比如一个区间的长度为k,那么他操作次数为k - 1,所以总的操作次数就是(n - 区间的个数). 那么要算出区…

C. Vanya and Exams Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/492/problem/C Description Vanya wants to pass n exams and get the academic scholarship. He will get the scholarship if the average grade mark for all the ex…

C. Wilbur and Points Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/596/problem/C Description Wilbur is playing with a set of n points on the coordinate plane. All points have non-negative integer coordinates. Moreover, if…

A. Warrior and Archer Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/594/problem/A Description In the official contest this problem has a different statement, for which jury's solution was working incorrectly, and for this…

B. OR in Matrix Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/486/problem/B Description Let's define logical OR as an operation on two logical values (i. e. values that belong to the set {0, 1}) that is equal to 1 if eith…

E. Anton and Ira Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/584/problem/E Description Anton loves transforming one permutation into another one by swapping elements for money, and Ira doesn't like paying for stupid game…