dinic 网络流模板

//密集图
const int maxn = 240;
int cap[maxn][maxn];
int layer[maxn];
int st, en;//start point, end point

bool count_layer() {
queue<int> q;  q.push(st);
memset(layer, -1, sizeof(layer));
layer[st] = 0;

while(!q.empty()) {
int v = q.front();  q.pop();
for(int i = st; i <= en; i++) {
if(layer[i] == -1 && cap[v][i] > 0) {
layer[i] = layer[v]+1;
if(i == en)
return true;
q.push(i);
}
}
}
return false;
}
int dfs(int root, int cur_flow) {
int dt = cur_flow;//the rest of cur_flow
if (root == en) return dt;
for (int i = 0; i <= en; i++) {
if (cap[root][i] > 0 && layer[i] == layer[root]+1) {
int flow = dfs(i, min(dt, cap[root][i]));
cap[root][i] -= flow;
cap[i][root] += flow;
dt -= flow;
}
}
return cur_flow - dt;
}
int dinic() {
int ans = 0;
while(count_layer())
ans += dfs(st, INF);
return ans;
}