码迷,mamicode.com
首页 > 其他好文 > 详细

HDOJ3549-Flow Problem(最大流)

时间:2017-06-02 12:45:06      阅读:230      评论:0      收藏:0      [点我收藏+]

标签:source   lines   clr   com   script   direct   for   pre   ble   

Problem Description

Network flow is a well-known difficult problem for ACMers. Given a graph, your task is to find out the maximum flow for the weighted directed graph.

 

Input

The first line of input contains an integer T, denoting the number of test cases.For each test case, the first line contains two integers N and M, denoting the number of vertexes and edges in the graph. (2 <= N <= 15, 0 <= M <= 1000)Next M lines, each line contains three integers X, Y and C, there is an edge from X to Y and the capacity of it is C. (1 <= X, Y <= N, 1 <= C <= 1000)

 

Output

For each test cases, you should output the maximum flow from source 1 to sink N.

 

Sample Input

2
3 2
1 2 1
2 3 1
3 3
1 2 1
2 3 1
1 3 1

 

Sample Output

Case 1: 1
Case 2: 2

 技术分享

Code:

技术分享
 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 #define CLR(x , v)      memset(x , v , sizeof(x))
 5 
 6 static const int OO = 0x3fffffff;
 7 
 8 static const int MAXN = 1e3 + 10;
 9 
10 int n , m;
11 int cap[MAXN][MAXN];
12 int flow[MAXN][MAXN];
13 int add[MAXN];
14 queue<int> q;
15 int pre[MAXN];
16 int main()
17 {
18     int t;
19     scanf("%d" , &t);
20     for(int c = 1 ; c <= t ; ++c)
21     {
22         int ans = 0;
23         CLR(cap , 0);
24         CLR(flow , 0);
25         CLR(pre , 0);
26         while(!q.empty())
27             q.pop();
28         scanf("%d%d" , &n , &m);
29         for(int i = 1 ; i <= m ; ++i)
30         {
31             int a , b , c;
32             scanf("%d%d%d" , &a , &b , &c);
33             cap[a][b] += c;
34         }
35 
36         for(;;)
37         {
38             CLR(add , 0);
39             add[1] = OO;
40             q.push(1);
41             while(!q.empty())
42             {
43                 int u = q.front();
44                 q.pop();
45                 for(int i = 1 ; i <= n ; ++i)
46                 {
47                     if(!add[i] && cap[u][i] > flow[u][i])
48                     {
49                         pre[i] = u;
50                         q.push(i);
51                         add[i] = min(add[u] , cap[u][i] - flow[u][i]);
52                     }
53                 }
54             }
55 
56             if(!add[n])
57                 break;
58 
59             for(int i = n ; i != 1 ; i = pre[i])
60             {
61                 flow[pre[i]][i] += add[n];
62                 flow[i][pre[i]] -= add[n];//反向弧
63             }
64 
65             ans += add[n];
66         }
67 
68         printf("Case %d: %d\n" , c , ans);
69     }
70 }
View Code

 

HDOJ3549-Flow Problem(最大流)

标签:source   lines   clr   com   script   direct   for   pre   ble   

原文地址:http://www.cnblogs.com/jianglingxin/p/6932641.html

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!