题目链接:http://codeforces.com/problemset/problem/1249/B2 思路:用并查集模拟链表,把关系串联起来,如果成环,则满足题意.之后再用并查集合并一个链,一个链代表 一个集合,一个集合有共同的祖先,一个集合答案相同,则输出答案时候只需要输出该元素属于哪一个集合,那个集合有几个元素 就可以了. #include <stdio.h> #include <iostream> using namespace std; ; int fa[N]; in…

The only difference between easy and hard versions is constraints. There are nn kids, each of them is reading a unique book. At the end of any day, the ii-th kid will give his book to the pipi-th kid (in case of i=pii=pi the kid will give his book to…

The only difference between easy and hard versions is constraints. There are nn kids, each of them is reading a unique book. At the end of any day, the ii-th kid will give his book to the pipi-th kid (in case of i=pii=pi the kid will give his book to…

B2. Character Swap (Hard Version) This problem is different from the easy version. In this version Ujan makes at most 2…

[Codeforces 1214A]Optimal Currency Exchange(贪心) 题面 题面较长,略 分析 这个A题稍微有点思维难度,比赛的时候被孙了一下 贪心的思路是,我们换面值越小的货币越优.如有1,2,5,10,20,50,那么我们尽量用面值为1的.如果我们把原始货币换成面值为x的货币,设汇率为d,那么需要的原始货币为dx的倍数.显然dx越小,剩下的钱,即n取模dx会尽量小. 然后就可以枚举换某一种货币的数量,时间复杂度\(O(\frac{n}{d})\) 代码 #inclu…

[Codeforces 1214D]Treasure Island(dfs) 题面 给出一个n*m的字符矩阵,'.'表示能通过,'#'表示不能通过.每步可以往下或往右走.问至少把多少个'.'变成'#',才能让从(1,1)出发不能到达(n,m) \(n \times m \leq 10^6\) 分析 第一眼还以为是最小割,一看数据范围感觉会TLE.实际上搜索就可以了. 首先发现答案肯定是0,1,2中的一个(输出rand()%3),因为最多用2个'#',把(1,1)右侧和下方堵住就可以了. 然后注意…

链接: https://codeforces.com/contest/1247/problem/B2 题意: The only difference between easy and hard versions is constraints. The BerTV channel every day broadcasts one episode of one of the k TV shows. You know the schedule for the next n days: a sequen…

链接: https://codeforces.com/contest/1234/problem/B2 题意: The only difference between easy and hard versions are constraints on n and k. You are messaging in one of the popular social networks via your smartphone. Your smartphone can show at most k most…

This problem is different from the easy version. In this version Ujan makes at most 2n2n swaps. In addition, k≤1000,n≤50k≤1000,n≤50 and it is necessary to print swaps themselves. You can hack this problem if you solve it. But you can hack the previou…

Codeforces 1108E2 E2. Array and Segments (Hard version) Description: The only difference between easy and hard versions is a number of elements in the array. You are given an array \(a\) consisting of \(n\) integers. The value of the \(i\)-th element…