网络最大流（SAP）【模板】

#include <stdio.h>
#include <string.h>
const int inf=1<<30;
#define MAXM 2000

struct edge
{
int from, to, val, next;
}e[MAXM*MAXM];

int v[MAXM];
int n,m,len,st,ed;   //st = 源点  ed = 汇点

void init()
{
len = 0;
memset(v,-1,sizeof(v));
}

void insert(int from, int to, int va)
{
e[len].from = from, e[len].to = to;
e[len].val = va;
e[len].next = v[from];
v[from] = len++;
e[len].from = to, e[len].to = from;
e[len].val = 0;
e[len].next = v[to];
v[to] = len++;
}

int sap()
{
int dist[MAXM],now[MAXM],cnt[MAXM],pre[MAXM],cur[MAXM];
int tot_flow;
int now_flow, found, min;
int i, j, t;
memset(dist, 0, sizeof(dist));
memset(now, -1, sizeof(now));
memset(cnt, 0, sizeof(cnt));
i = st;
tot_flow = 0; now_flow = inf;
cnt[0] = n;
while(dist[st] < n)
{
cur[i] = now_flow; found = 0;
if(now[i] == -1) t = v[i];
else t = now[i];
while(t != -1)
{
j = e[t].to;
if(e[t].val > 0 && dist[j] + 1 == dist[i])
{
found = 1; now[i] = t;
if(e[t].val < now_flow) now_flow = e[t].val;
pre[j] = t; i = j;
if(i == n+m+1)
{
tot_flow += now_flow;
while(i != st)
{
e[pre[i]].val -= now_flow;
e[pre[i]^1].val += now_flow;
i = e[pre[i]].from;
}
now_flow = inf;
}                 break;
}             t = e[t].next;
}
if(found) continue;
if(--cnt[dist[i]] == 0) break;
min = n - 1;
t = v[i];
while(t != -1)
{
if(e[t].val > 0 && dist[e[t].to] < min)
{
min = dist[e[t].to];
now[i] = t;
}
t = e[t].next;
}         dist[i] = min + 1;
cnt[dist[i]]++;
if(i != st)
{
i = e[pre[i]].from;
now_flow = cur[i];
}
}
return tot_flow;
}

int main()
{
int x,y,va;
while (scanf("%d%d",&n,&m),n+m)
{
init();
st = 1;
ed = n;
while (m--)
{
scanf("%d%d%d",&x,&y,&va);
insert(x,y,va);
}
printf("%d/n",sap());
}
return 0;
}