
Code
#include <bits/stdc++.h>
using namespace std;
const int N = 1010, M = 20020;
int n, m, S, T, d[N], pre[N];
int h[N], e[M], f[M], ne[M], idx;
bool vis[N];
void add(int a, int b, int c)
{
e[idx] = b, f[idx] = c, ne[idx] = h[a], h[a] = idx++;
e[idx] = a, f[idx] = 0, ne[idx] = h[b], h[b] = idx++;
}
bool bfs()
{
memset(vis, false, sizeof vis);
queue<int> q;
q.push(S), vis[S] = true, d[S] = 0x3f3f3f3f;
while (q.size())
{
int t = q.front(); q.pop();
for (int i = h[t]; i != -1; i = ne[i])
{
int ver = e[i];
if (!vis[ver] && f[i])
{
vis[ver] = true;
d[ver] = min(d[t], f[i]);
pre[ver] = i;
if (ver == T) return true;
q.push(ver);
}
}
}
return false;
}
int EK()
{
int res = 0;
while (bfs())
{
res += d[T];
for (int i = T; i != S; i = e[pre[i] ^ 1])
f[pre[i]] -= d[T], f[pre[i] ^ 1] += d[T];
}
return res;
}
int main()
{
memset(h, -1, sizeof h);
cin >> n >> m >> S >> T;
while (m--)
{
int a, b, c; cin >> a >> b >> c;
add(a, b, c);
}
cout << EK() << endl;
return 0;
}