而是Div2的最后一题,当时打比赛的时候还不会最大流.自己能够把它写出来然后1A还是很开心的. 题意: 有n个不小于2的整数,现在要把他们分成若干个圈.在每个圈中,数字的个数不少于3个,而且相邻的两个数之和是质数. 分析: 因为每个数都不小于2,所以相加得到的质数一定是奇数,那么在某个圈中,一定是奇偶相间的. 也就是 奇数相邻的两个数是偶数,偶数相邻的两个数是奇数. 所以一个圈中的数字一定是偶数个,所有的输入中也必须是偶数和奇数的个数相同才可能有解. 这转化为了二分图匹配,其中X是奇数,Y是偶数…

E. Fox And Dinner time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Fox Ciel is participating in a party in Prime Kingdom. There are n foxes there (include Fox Ciel). The i-th fox is ai year…

D. Fox And Jumping 题目连接: http://codeforces.com/contest/510/problem/D Description Fox Ciel is playing a game. In this game there is an infinite long tape with cells indexed by integers (positive, negative and zero). At the beginning she is standing at…

C. Fox And Names 题目连接: http://codeforces.com/contest/510/problem/C Description 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…

B. Fox And Two Dots 题目连接: http://codeforces.com/contest/510/problem/B Description Fox Ciel is playing a mobile puzzle game called "Two Dots". The basic levels are played on a board of size n × m cells, like this: Each cell contains a dot that ha…

A. Fox And Snake 题目连接: http://codeforces.com/contest/510/problem/A Description Fox Ciel starts to learn programming. The first task is drawing a fox! However, that turns out to be too hard for a beginner, so she decides to draw a snake instead. A sna…

http://codeforces.com/problemset/problem/510/B #include "cstdio" #include "cstring" int r,c; ][]; ][]; int mark; ]={,-,,},dy[]={,,,-}; int judge(int x,int y) { ||x>=r||y<||y>=c) ; ; } void dfs(int x,int y,int perX,int perY) {…

题目传送门 /* DFS:每个点四处寻找,判断是否与前面的颜色相同,当走到已走过的表示成一个环 */ #include <cstdio> #include <iostream> #include <cstring> #include <string> #include <map> #include <algorithm> #include <vector> #include <set> #include <…

题目传送门 /* 水题 找规律输出 */ #include <cstdio> #include <iostream> #include <cstring> #include <string> #include <map> #include <algorithm> #include <vector> #include <set> #include <cmath> using namespace std…

题目传送门 /* 给出n个字符串,求是否有一个“字典序”使得n个字符串是从小到大排序 拓扑排序 详细解释:http://www.2cto.com/kf/201502/374966.html */ #include <cstdio> #include <iostream> #include <cstring> #include <string> #include <map> #include <algorithm> #include &…