今天老师(orz sansirowaltz)让我们做了很久之前的一场Codeforces Round #257 (Div. 1),这里给出A~C的题解,对应DIV2的C~E. A.Jzzhu and Chocolate time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Jzzhu has a big rectangular cho…

题目链接:http://codeforces.com/problemset/problem/449/C 给你n个数,从1到n.然后从这些数中挑选出不互质的数对最多有多少对. 先是素数筛,显然2的倍数的个数是最多的,所以最后处理.然后处理3,5,7,11...的倍数的数,之前已经挑过的就不能再选了.要是一个素数p的倍数个数是奇数,就把2*p给2 的倍数.这样可以满足p倍数搭配的对数是最优的.最后处理2的倍数就行了. #include <bits/stdc++.h> using namespace…

题目链接:http://codeforces.com/problemset/problem/450/B 题意很好懂,矩阵快速幂模版题. /* | 1, -1 | | fn | | 1, 0 | | fn-1 | */ #include <iostream> #include <cstdio> #include <cstring> using namespace std; typedef __int64 LL; LL mod = 1e9 + ; struct data {…

主题链接:http://codeforces.com/problemset/problem/449/A ---------------------------------------------------------------------------------------------------------------------------------------------------------- 欢迎光临天资小屋:http://user.qzone.qq.com/593830943…

题目链接:http://codeforces.com/problemset/problem/450/A ---------------------------------------------------------------------------------------------------------------------------------------------------------- 欢迎光临天资小屋:http://user.qzone.qq.com/593830943…

题目链接:http://codeforces.com/problemset/problem/450/B B. Jzzhu and Sequences time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Jzzhu has invented a kind of sequences, they meet the following pr…

A - Jzzhu and Children 找到最大的ceil(ai/m)即可 #include <iostream> #include <cmath> using namespace std; int main(){ int n,m; cin >> n >> m; ; ; ; i < n; ++ i){ cin >> a; if(maxv <= ceil(a/m)){ maxv = ceil(a/m); maxIdx = i+;…

题意:n个城市,中间有m条道路(双向),再给出k条铁路,铁路直接从点1到点v,现在要拆掉一些铁路,在保证不影响每个点的最短距离(距离1)不变的情况下,问最多能删除多少条铁路 分析:先求一次最短路,铁路的权值大于该点最短距离的显然可以删去,否则将该条边加入图中,再求最短路,记录每个点的前一个点,然后又枚举铁路,已经删去的就不用处理了,如果铁路权值大于该点最短距离又可以删去,权值相等时,该点的前一个点如果不为1,则这个点可以由其他路到达,这条铁路又可以删去. 由于本题中边比较多,最多可以有8x10^…

B. Jzzhu and Sequences time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Jzzhu has invented a kind of sequences, they meet the following property: You are given x and y, please calculate fn m…

A. Jzzhu and Children time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output There are n children in Jzzhu's school. Jzzhu is going to give some candies to them. Let's number all the children from…