C. Mail Stamps Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/problemset/problem/29/C Description One day Bob got a letter in an envelope. Bob knows that when Berland's post officers send a letter directly from city «A» to city «B…

传送门 •题意 给你两个数组 p,q ,分别存放 1~n 的某个全排列: 让你根据这两个数组构造一个字符串 S,要求: (1)$\forall i \in [1,n-1],S_{pi}\leq S _{pi+1}  ,\forall i \in [1,n-1],S_{qi} \leq S _{qi+1}$ (2)字符串 S 至少包含 k 个不同的小写字母: •思路 类似于牛客第五场的H 不过由于这个不知道字母是什么,需要利用强联通分解, 把属于同一个强联通块的位置置于同一个字母, 然后根据前后关…

题目链接:http://codeforces.com/problemset/problem/510/C Fox Ciel is going to publish a paper on FOCS (Foxes Operated Computer Systems, pronounce: "Fox"). She heard a rumor: the authors list on the paper is always sorted in the lexicographical order.…

E. Minimal Labels time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output You are given a directed acyclic graph with n vertices and m edges. There are no self-loops or multiple edges between any p…

Anna and Maria are in charge of the math club for junior students. When the club gathers together, the students behave badly. They've brought lots of shoe laces to the club and got tied with each other. Specifically, each string ties together two stu…

B. Drazil and Tiles 题目连接: http://codeforces.com/contest/516/problem/B Description Drazil created a following problem about putting 1 × 2 tiles into an n × m grid: "There is a grid with some cells that are empty and some cells that are occupied. You s…

Problem   Codeforces #541 (Div2) - D. Gourmet choice Time Limit: 2000 mSec Problem Description Input Output The first line of output should contain "Yes", if it's possible to do a correct evaluation for all the dishes, or "No" otherwis…

D. Gourmet choice 链接:http://codeforces.com/contest/1131/problem/D 思路: =  的情况我们用并查集把他们扔到一个集合,然后根据 > < 跑拓扑排序,根据拓扑排序的结果从小到大填数字就好了,需要注意的细节写在代码注释里了 代码: #include<bits/stdc++.h> using namespace std; ; int f[M],n,m; set<int>st[M]; vector<int&…

https://codeforces.com/contest/1131/problem/D 题意 给你一个n*m二维偏序表,代表x[i]和y[j]的大小关系,根据表构造大小分别为n,m的x[],y[],使得两个数组中最大的数尽量小 题解 按照偏序表,构造出从小到大的拓扑图 如何解决相等的数的偏序关系? 用并查集缩点后再进行拓扑排序 如何解决最大的数最小? 只需要使得同一层的数相同就行,可以一批处理栈中的元素,对于一批栈中的元素产生的新点,先放进一个容器里,然后等到这批栈清空了,再把这个容器中的点…

E. Tree Folding 题目连接: http://codeforces.com/contest/765/problem/E Description Vanya wants to minimize a tree. He can perform the following operation multiple times: choose a vertex v, and two disjoint (except for v) paths of equal length a0 = v, a1,…