CF954D Fight Against Traffic 题意描述: 给你一张无向图,一共有n个点(2 <= n <= 1000),由m条边连接起来(1 <= m <= 10000),现在要在任意一对没有连边的点之间连上一条边,并且保证s到t之间的最短路径长度不变(最短路径长度表示s到t最少经过的边的数量)(1 <= s,t <= n , s≠t),请你求出一共有多少条这样的边. 被水题成功报复... code: #include <iostream> #i…

题目链接:Fight Against Traffic 题意:有n个点个m条双向边,现在给出两个点S和T并要增加一条边,问增加一条边且S和T之间距离不变短的情况有几种? 题解:首先dfs求一下S到其他点和T到其他点的最短路(好久不写有点手生@.@),然后遍历所有的建边的情况,假设在i和j两个点之间建边则要满足 ds[i] + 1 + dt[j] > ds[T] && ds[j] + 1 + dt[i] > ds[T]. #include<bits/stdc++.h>…

Description 题目链接 Solution 从起点和终点分别做一次最短路并记录结果 枚举每一条可能的边判断 Code #include <cstdio> #include <algorithm> #include <queue> #include <cstring> #define N 1010 using namespace std; struct info{int to,nex;}e[N*2]; int n,m,s,t,tot,head[N],d…

题目链接:http://codeforces.com/contest/954/problem/D 题意 给出n个顶点,m条边,一个起点编号s,一个终点编号t 现准备在这n个顶点中多加一条边,使得st之间距离不变 问加边的方案数是多少 思路 想了半天才出思路,头一次打比赛时通过图论的题,挺高兴 因为是加一条边,所以我们可以考虑把这个新边的两端点进行更新 现用两个dist,一个是从起点开始的单源最短路dist[0],一个是从终点开始的单源最短路dist[1] 对于一个新边的两端点ab,我们只用判断是…

题目链接 http://codeforces.com/contest/954/problem/D 题目大意 n m s t 分别为点的个数, 边的个数,以及两个特殊的点 要求s与t间的距离在新增一条边下不变 基本思路 用dj算法由s 到 t两个点分别进行一次计算 得出每个点到s与t的最短值 遍历计算每两个没建立联系的边建立联系后,s与t的距离,并与初始时距离比较 若不变则记录(s与t的值必定为新建经由新建这条边的数值或原始值中最小一个) #include <stdio.h> #include…

Discription Little town Nsk consists of n junctions connected by m bidirectional roads. Each road connects two distinct junctions and no two roads connect the same pair of junctions. It is possible to get from any junction to any other junction by th…

从这里开始 小结 题目列表 Problem A Diagonal Walking Problem B String Typing Problem C Matrix Walk Problem D Fight Against Traffic Problem E Water Taps Problem F Runner's Problem Problem G Castle Defense Problem H Path Counting Problem I Yet Another String Match…

A. Diagonal Walking 题意 将一个序列中所有的\('RU'\)或者\('UR'\)替换成\('D'\),问最终得到的序列最短长度为多少. 思路 贪心 Code #include <bits/stdc++.h> #define F(i, a, b) for (int i = (a); i < (b); ++i) #define F2(i, a, b) for (int i = (a); i <= (b); ++i) #define dF(i, a, b) for (…

Extended Traffic 题目链接: http://acm.hust.edu.cn/vjudge/contest/122685#problem/O Description Dhaka city is getting crowded and noisy day by day. Certain roads always remain blocked in congestion. In order to convince people avoid shortest routes, and he…

103. Traffic Lights Time limit per test: 0.25 second(s)Memory limit: 4096 kilobytes input: standardoutput: standard In the city of Dingilville the traffic is arranged in an unusual way. There are junctions and roads connecting the junctions. There is…