Ikki's Story I - Road Reconstruction 题意:有N个顶点和M条边N, M (N ≤ 500, M ≤ 5,000)  ,试图改变图中的一条边使得从0到N-1的流量增加:问这样的边有几条? 思路:刚最大流入门,之后一看就觉得满流的边就是答案..真是太天真了.之后看了题解,发现满流只是前提(即使满流是几次残量的叠加也是一样),还有一个条件是,该路径的最大流量只受该边影响:即可以从S和T遍历到该边的两个端点,这就是为什么之后还要dfs给点涂色的原因:涂色前要对残余网络

find the safest road Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 9144    Accepted Submission(s): 3225 Problem Description XX星球有很多城市,每个城市之间有一条或多条飞行通道,但是并不是所有的路都是很安全的,每一条路有一个安全系数s,s是在 0 和 1

Qin Shi Huang's National Road System Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 3979    Accepted Submission(s): 1372 Problem Description During the Warring States Period of ancient China(4

D - Restoring Road Network Time limit : 2sec / Memory limit : 256MB Score : 500 points Problem Statement In Takahashi Kingdom, which once existed, there are N cities, and some pairs of cities are connected bidirectionally by roads. The following are

In Takahashi Kingdom, which once existed, there are N cities, and some pairs of cities are connected bidirectionally by roads. The following are known about the road network: People traveled between cities only through roads. It was possible to reach

B - Chris and Road Crawling in process... Crawling failed Time Limit:2000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u Submit Status Practice _ uDebug Description Input Output Sample Input Sample Output Hint Description And while Mis

分析:http://www.cnblogs.com/wally/archive/2013/02/04/2892194.html 这个题就是多一个限制,就是求包含每条边的最小生成树,这个求出原始最小生成树然后查询就好了 然后预处理那个数组是O(n^2)的,这样总时间复杂度是O(n^2+m) 这是因为这个题n比较小,如果n大的时候,就需要路径查询了,比如LCA 或者树链剖分达到O(mlogn) #include <iostream> #include <algorithm> #incl

枚举作为magic road的边,然后求出A/B. A/B得在大概O(1)的时间复杂度求出,关键是B,B是包含magic road的最小生成树. 这么求得: 先在原图求MST,边总和记为s,顺便求出MST上任意两点路径上的最长边d[i][j]. 当(u,v)是magic road时, 如果它在原本的MST上,则B就等于s-原(u,v)的权,而原(u,v)的权其实就是d[u][v]: 如果它不在原本的MST上,则B就等于s-d[u][v]+0. 总之就是一个式子:B=s-d[u][v]. 于是,在

find the most comfortable road Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 5359    Accepted Submission(s): 2327 Problem Description XX 星有许多城市,城市之间通过一种奇怪的高速公路SARS(Super Air Roam Structure---超

find the safest road Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 9168    Accepted Submission(s): 3238 Problem Description XX星球有很多城市,每个城市之间有一条或多条飞行通道,但是并不是所有的路都是很安全的,每一条路有一个安全系数s,s是在 0 和 1