A. Maze 题目连接: http://codeforces.com/contest/377/problem/A Description Pavel loves grid mazes. A grid maze is an n × m rectangle maze where each cell is either empty, or is a wall. You can go from one cell to another only if both cells are empty and h…

题目链接:http://codeforces.com/problemset/problem/377/A 题解: 有tot个空格(输入时统计),把其中k个空格变为wall,问怎么变才能使得剩下的空格依然为连通的.把问题反过来,其实就是求tot-k的连通图.dfs:在搜索过的空格中做个标记,同时更新连通个数. 代码如下: #include<cstdio>//hdu3183 CodeForces 377A dfs #include<cstring> #include<cmath&g…

C. Xor-tree Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/430/problem/C Description Iahub is very proud of his recent discovery, propagating trees. Right now, he invented a new tree, called xor-tree. After this new revolu…

D. MADMAX time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output As we all know, Max is the best video game player among her friends. Her friends were so jealous of hers, that they created an actu…

题目链接:http://codeforces.com/contest/767/problem/C 题解:类似于提着一串葡萄,用剪刀剪两条藤,葡萄分成了三串.问怎样剪才能使三串葡萄的质量相等. 首先要做的就是统计葡萄的总质量tot.之后就是找到两子串质量为(tot/3)的葡萄(如果除不尽,则必定找不到),那么剩下的就是dfs搜索了. 我一开始的做法是先建一棵记录子树质量和的树,然后再从上往下dfs,如果找到了,就把它剪掉.后来发现被剪掉的那一串可能就含有两串质量为(tot/3)的葡萄(这里质量 可…

377A Maze 大意: 给定棋盘, 保证初始所有白格连通, 求将$k$个白格变为黑格, 使得白格仍然连通. $dfs$回溯时删除即可. #include <iostream> #include <functional> #include <sstream> #include <algorithm> #include <cstdio> #include <math.h> #include <set> #include &…

题意:给出一棵树,共有n个节点,其中根节点是Kefa的家,叶子是restaurant,a[i]....a[n]表示i节点是否有猫,问:Kefa要去restaurant并且不能连续经过m个有猫的节点有多少条路径: 思路:先用vector数组建树: 再dfs..(第一次用vector建树,还看了别人的代码,果然是zz): 代码: #include <bits/stdc++.h> #define ll long long #define MAXN 100000+10 using namespace…

题目链接: http://codeforces.com/contest/378/problem/E 题意: dota选英雄,现在有n个英雄,m个回合,两支队伍: 每一回合两个选择: b 1,队伍一ban掉一个英雄,或是跳过这个回合 p 1,队伍1选一个英雄 现在每个队伍都是最优决策,问最后队伍一的英雄实力和-队伍二的英雄实力和. 题解: 状压dp,决策要倒过来做,也就是dp出后面回合的决策的基础上设计出对自己当前回合对自己最有利的决策.. 注意:只有top m的英雄有可能被选,其他的都不可能被选…

D. Fedor and Essay time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output After you had helped Fedor to find friends in the «Call of Soldiers 3» game, he stopped studying completely. Today, the E…

D. Developing Game 题目连接: http://www.codeforces.com/contest/377/problem/D Description Pavel is going to make a game of his dream. However, he knows that he can't make it on his own so he founded a development company and hired n workers of staff. Now…