题目链接: D. Bear and Two Paths time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Bearland has n cities, numbered 1 through n. Cities are connected via bidirectional roads. Each road connects tw…

D. Bear and Two Paths 题目连接: http://www.codeforces.com/contest/673/problem/D Description Bearland has n cities, numbered 1 through n. Cities are connected via bidirectional roads. Each road connects two distinct cities. No two roads connect the same p…

D. Bear and Two Paths time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Bearland has n cities, numbered 1 through n. Cities are connected via bidirectional roads. Each road connects two dist…

D. Bear and Two Paths time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Bearland has n cities, numbered 1 through n. Cities are connected via bidirectional roads. Each road connects two dist…

[Codeforces 1005F]Berland and the Shortest Paths(最短路树+dfs) 题面 题意:给你一个无向图,1为起点,求生成树让起点到其他个点的距离最小,距离最小的生成树可能有多个.给定k,如果方案数比k小就输出全部方案,否则输出k种方案. 分析 先跑最短路,对于每个点找到它在最短路树上可能的父亲.即对于\((x,y) \in E,dist(y)=dist(x)+len(x,y)\).那么y在最短路上可能的父亲就是x.说"可能"是因为最短路树可能不…

题目链接: http://codeforces.com/contest/673/problem/D 题意: 给四个不同点a,b,c,d,求是否能构造出两条哈密顿通路,一条a到b,一条c到d. 题解: 构造法,看例子: input: 5 6 5 2 4 1 output: 5 4 3 1 2 4 5 3 2 1 所以只要满足k>=n+1,就可以构造出来答案. #include<iostream> #include<cstring> #include<cstdio>…

<题目链接> 题目大意:给定一个无向图,该无向图不含自环,且无重边.现在要你将这个无向图定向,使得不存在任何一条路径长度大于等于2.然后根输入边的顺序,输出构造的有向图.如果构造的边与输入的方向一致,就输出1,方向不一致就输出0. 解题分析:因为定向后的图不能存在长度大于等于2的路径,所以我们直接对原图进行奇偶染色.如果碰到了奇环,就直接输出"NO",否则就对该图奇偶染色,进行地定向.$col[u]$表示以$u$为起点的边所染的颜色. #include <bits/s…

D. Optimal Number Permutation 题目连接: http://www.codeforces.com/contest/622/problem/D Description You have array a that contains all integers from 1 to n twice. You can arbitrary permute any numbers in a. Let number i be in positions xi, yi (xi < yi) i…

Problem H. Hard TestTime Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100342/attachments Description Andrew is having a hard time preparing his 239-th contest for Petrozavodsk. This time the solution to the problem is based on Di…

C. Necklace 题目连接: http://www.codeforces.com/contest/613/problem/C Description Ivan wants to make a necklace as a present to his beloved girl. A necklace is a cyclic sequence of beads of different colors. Ivan says that necklace is beautiful relative…