题意 求一个生成树,使得任意点到源点的最短路等于原图中的最短路.再让这个生成树边权和最小. http://codeforces.com/contest/545/problem/E 思路 先Dijkstra一下,再对每个点连的边判断是不是最短路上的边,如果是那再贪心取最小的边即可. 代码 #include<bits/stdc++.h> using namespace std; #define ll long long const ll inf=1e18; const int N=6e5+5; s…

题目大意: 给出一个无向无环连通图(树),n个点n-1条边,m次查询,每次询问给出一个集合,问集合里的树是否都在同一条链上(即能否不重复的走一条边而遍历整个点集) 思路:通过求lca,若有三个点x,y,z 如果满足dix(x,y)+dix(y,z) == dix(x,z),说明此时y位于x,z之间,此时他们就在一条链上,只需要枚举除x,y以外剩下的n-2个点 判断是否满足类似的条件,每次不断跟新x,y的值使其成为一条链上的两个端点. 1 # include<iostream> 2 # incl…

Bakery 题目链接: http://codeforces.com/contest/707/problem/B Description Masha wants to open her own bakery and bake muffins in one of the n cities numbered from 1 to n. There are m bidirectional roads, each of whose connects some pair of cities. To bake…

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…

Codeforces Round #580 (Div. 1) https://codeforces.com/contest/1205 A. Almost Equal 随便构造一下吧...太水了不说了,放个代码吧. #include<bits/stdc++.h> using namespace std; void read(int &x) { x=0;int f=1;char ch=getchar(); for(;!isdigit(ch);ch=getchar()) if(ch=='-'…

Codeforces Round #366 (Div. 2) A I hate that I love that I hate it水题 #I hate that I love that I hate it n = int(raw_input()) s = "" a = ["I hate that ","I love that ", "I hate it","I love it"] for i in ran…

Codeforces Round #354 (Div. 2) Problems     # Name     A Nicholas and Permutation standard input/output 1 s, 256 MB    x3384 B Pyramid of Glasses standard input/output 1 s, 256 MB    x1462 C Vasya and String standard input/output 1 s, 256 MB    x1393…

直达–>Codeforces Round #368 (Div. 2) A Brain’s Photos 给你一个NxM的矩阵,一个字母代表一种颜色,如果有”C”,”M”,”Y”三种中任意一种就输出”#Color”,如果只有”G”,”B”,”W”就输出”#Black&White”. #include <cstdio> #include <cstring> using namespace std; const int maxn = 200; const int INF =…

 cf之路,1,Codeforces Round #345 (Div. 2) ps:昨天第一次参加cf比赛,比赛之前为了熟悉下cf比赛题目的难度.所以做了round#345连试试水的深浅.....       其实这个应该是昨天就写完的,不过没时间了,就留到了今天.. 地址:http://codeforces.com/contest/651/problem/A A. Joysticks time limit per test 1 second memory limit per test 256…

Codeforces Round #279 (Div. 2) 做得我都变绿了! Problems     # Name     A Team Olympiad standard input/output 1 s, 256 MB  x2377 B Queue standard input/output 2 s, 256 MB  x1250 C Hacking Cypher standard input/output 1 s, 256 MB  x740 D Chocolate standard in…