Billing flow mcmf template version 2.0

Address: HDU 3488

This evening, I found that the previous billing template was incorrect ....... Vulnerabilities .... But they all have so many questions .. Think about it too .. There are not many traffic fees, and all traffic is 1. This vulnerability will not be affected. In the past, the minimum traffic found after the minimum fee is increased is the minimum traffic of all routes, not necessarily the minimum traffic that can reach the settlement point .. However, if the traffic is 1 .. As long as the side does not flow completely, the minimum traffic will certainly be 1. If it has already flow completely .. That's meaningless .. The maximum stream has been reached. So this vulnerability has never been detected...

So how should we improve it. That is, like the shortest method, marking a cost array changes as the path changes. In this case, the final

F [sink] must be the minimum traffic that reaches the sink. Everything else is correct. If you change this area, it will be OK.

In order to prevent the previous code from harming people... Let's find a new time .. Tut

The template is as follows;

#include <iostream>#include <stdio.h>#include <string.h>#include <stdlib.h>#include <math.h>#include <ctype.h>#include <queue>#include <map>#include <algorithm>using namespace std;const int INF=0x3f3f3f3f;int head[500], source, sink, cnt, flow, cost;int d[500], pre[500], q[1000000], cur[500], vis[500], f[500];struct node{    int u, v, cap, cost, next;}edge[1000000];void add(int u, int v, int cap, int cost){    edge[cnt].v=v;    edge[cnt].cap=cap;    edge[cnt].cost=cost;    edge[cnt].next=head[u];    head[u]=cnt++;    edge[cnt].v=u;    edge[cnt].cap=0;    edge[cnt].cost=-cost;    edge[cnt].next=head[v];    head[v]=cnt++;}int spfa(){    memset(d,INF,sizeof(d));    memset(vis,0,sizeof(vis));    int minflow=INF, f1=0, f2=0, i;    q[f1++]=source;    f[source]=INF;    d[source]=0;    cur[source]=-1;    while(f1>=f2)    {        int u=q[f2++];        vis[u]=0;        for(i=head[u];i!=-1;i=edge[i].next)        {            int v=edge[i].v;            if(d[v]>d[u]+edge[i].cost&&edge[i].cap)            {                d[v]=d[u]+edge[i].cost;                f[v]=min(f[u],edge[i].cap);                cur[v]=i;                if(!vis[v])                {                    q[f1++]=v;                    vis[v]=1;                }            }        }    }    if(d[sink]==INF) return 0;    flow+=f[sink];    cost+=f[sink]*d[sink];    for(i=cur[sink];i!=-1;i=cur[edge[i^1].v])    {        edge[i].cap-=f[sink];        edge[i^1].cap+=f[sink];    }    return 1;}void mcmf(){    flow=cost=0;    while(spfa()) ;    printf("%d\n",cost);}int main(){    int T, n, m, i, j, a, b, c;    scanf("%d",&T);    while(T--)    {        scanf("%d%d",&n,&m);        memset(head,-1,sizeof(head));        cnt=0;        source=0;        sink=2*n+1;        flow=0;        cost=0;        for(i=1;i<=n;i++)        {            add(source,i,1,0);            add(i+n,sink,1,0);        }        while(m--)        {            scanf("%d%d%d",&a,&b,&c);            add(a,b+n,1,c);        }        mcmf();    }    return 0;}