和自己的比起来，感觉大牛的代码要精悍的多啊。
代码如下：
#include <stdio.h>
#include <string.h>
#define maxn 250
struct Map
{
int f;
int c;
}map[maxn][maxn];
int pre[maxn];
int q[maxn*maxn];
int v[maxn];
int N,M;
int s,t;
int abs( int x ){ return x > 0 ? x : -x ; }
int min( int x, int y ){ return x < y ? x : y; }
void init()
{
int i, S, E, C;
memset( map, 0, sizeof(map) );
for(i=0;i<N;i++)
{
scanf( "%d%d%d", &S, &E, &C );
map[S][E].c += C;
}
}
void solve()
{
int i,j;
int head,tail;
s = 1;
t = M;
while(true)
{
memset( pre, 0, sizeof(pre) );
head = 0, tail = 1;
q[0] = s;
v[s] = 1000000000;
pre[s] = s;
while( head < tail && pre[t] == 0 )
{
i = q[head];
for( j = 1; j <= M; j++ )
{
if( pre[j] == 0 )
{
if( map[i][j].f < map[i][j].c )
pre[j] = i , q[tail++] = j , v[j] = min( v[i], map[i][j].c-map[i][j].f );
else if( map[j][i].f > 0 )
pre[j] = -i, q[tail++] = j , v[j] = min( v[i], map[j][i].f );
}
}
head++;
}
if( pre[t] == 0 )break;
i = t;
while( i != s )
{
j = abs( pre[i] );
if( pre[i] > 0 )map[j][i].f += v[t];
else map[i][j].f -= v[t];
i = j;
}
}
int ans = 0;
for( i = 1; i <= M; i++ )ans += map[s][i].f;
printf("%d\n",ans);
}
int main()
{
while(scanf("%d%d",&N,&M)!=EOF)
{
init();
solve();
}
return 0;
}