[题目链接]:http://codeforces.com/problemset/problem/22/C [题意] 给你n个点; 要求你构造一个含m条边的无向图; 使得任意两点之间都联通; 同时,要求这张图; 在删掉第x个节点之后,会有一些点之间变成不联通的; (两点之间最多连一条边) [题解] 把v和某一个点x连在一起; 然后除了这两个点之外的其他n-2个点; 先每一个点都和v连一条边; 保证联通; 然后如果边数还有剩余; 就在那剩余的n-2个点之间一直连边,直到练成一个团(n-2个点的完全图…

[codeforces 415D]Mashmokh and ACM 题意:美丽数列定义:对于数列中的每一个i都满足:arr[i+1]%arr[i]==0 输入n,k(1<=n,k<=2000),问满足[数列长度是k && 数列中每一个元素arr[i]在1~n之间 && 数列中元素可以重复]的数列有多少个?结果对10^9+7取余 解题思路:dp[i][j]表示长度是j,最后一位是i的种数 if(kk%i==0) dp[kk][j+1]+=dp[i][j] #inc…

time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output A magic island Geraldion, where Gerald lives, has its own currency system. It uses banknotes of several values. But the problem is, the system i…

[题目链接]:http://codeforces.com/contest/527/problem/B [题意] 给你两个字符串; 允许你交换一个字符串的两个字符一次: 问你这两个字符串最少会有多少个位置上的字符不同 [题解] 考虑一次交换能够造成的结果 ->不同的字符个数减少1 ->不同的字符个数减少2 先考虑减少1 记录第一个字符串哪些字符和第二个字符串的不一样记录下来 然后扫描第二个字符串的每个字符,找到不同字符的位置,看看第二个字符串那个位置的字符有没有在第一个字符串里面出现过(刚才有记…

time limit per test1 second memory limit per test256 megabytes inputstandard input outputstandard output After seeing the "ALL YOUR BASE ARE BELONG TO US" meme for the first time, numbers X and Y realised that they have different bases, which co…

time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output This is an interactive problem. In the interaction section below you will find the information about flushing the output. The New Year tree of h…

time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output Ari the monster is not an ordinary monster. She is the hidden identity of Super M, the Byteforces' superhero. Byteforces is a country that consi…

time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output Dasha logged into the system and began to solve problems. One of them is as follows: Given two sequences a and b of length n each you need to wr…

time limit per test2 seconds memory limit per test256 megabytes inputstandard input outputstandard output Vika has an infinite sheet of squared paper. Initially all squares are white. She introduced a two-dimensional coordinate system on this sheet a…

[题目链接]:http://codeforces.com/contest/707/problem/E [题意] 给你一个n*m的方阵; 里面有k个联通块; 这k个联通块,每个连通块里面都是灯; 给你q个操作; 有以下两种类型 ①将第i个连通块里面灯取反 ②询问你(x1,y1)(x2,y2)这个矩形区域内灯的权值的和; [题解] 要用到二维的树状数组; 取反操作只要O(1)就能完成; 即先不管它是什么,取反就是了; 然后在询问的时候,直接用二维树状数组累加; 这里的累加可能是减也可能是加; 也可能…