欢迎参加——BestCoder周年纪念赛(高质量题目+多重奖励)
Flow Problem
Time Limit: 5000/5000 MS (Java/Others) Memory Limit: 65535/32768 K (Java/Others)
Total Submission(s): 10184 Accepted Submission(s): 4798
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
Author
HyperHexagon
Source
HyperHexagon‘s Summer Gift (Original tasks)
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#include<stdio.h> #include<string.h> #include<iostream> #include<algorithm> #include<queue> using namespace std; int dp[100][100],pre[100]; const int tmin=999999999; int maxflow; void EK(int start,int end,int n){ while(1){ queue<int>q; q.push(1); int minflow=tmin; memset(pre,0,sizeof(pre)); while(!q.empty()){ int u=q.front(); q.pop(); for(int i=1;i<=n;i++){ if(dp[u][i]>0&&!pre[i]){ pre[i]=u; q.push(i); } } } if(pre[end]==0) break; for(int i=end;i!=start;i=pre[i]){ minflow=min(dp[pre[i]][i],minflow); } for(int i=end;i!=start;i=pre[i]){ dp[pre[i]][i]-=minflow; dp[i][pre[i]]+=minflow; } maxflow+=minflow; } } int main(){ int count=0; int n,m; int t; scanf("%d",&t); while(t--){ scanf("%d%d",&n,&m); memset(dp,0,sizeof(dp)); memset(pre,0,sizeof(pre)); count++; int u,v,w; for(int i=1;i<=m;i++){ scanf("%d%d%d",&u,&v,&w); dp[u][v]+=w; } maxflow=0; EK(1,n,n); printf("Case %d: %d\n",count,maxflow); } return 0; }