网络流模板(更新中)

1.dinic

const int MAXN = 2e3 + 5;
const int INF = 0x3f3f3f3f;

struct Edge{
    int to,val,nxt;
}e[MAXN];

int head[MAXN], deep[MAXN];
int n, m, s, t, cnt;
ll res;

inline void init() {
    for (int i = 1; i <= n; i++) head[i] = -1;
    cnt = 0;
}

inline void add(int from, int to, int val) {
    e[cnt] = Edge{to, val, head[from]};
    head[from] = cnt++;
}

inline int bfs() { 
    for (int i = 2; i <= t; i++) deep[i] = -1;
    queue<int>q;
    deep[s] = 1;
    q.push(s);
    while (!q.empty()) {
        int front = q.front();
        q.pop();
        for (int i = head[front]; i != -1; i = e[i].nxt) {
            if (deep[e[i].to] == -1 && e[i].val) {
                deep[e[i].to] = deep[front] + 1;
                q.push(e[i].to);
            }
        }
    }
    return  (deep[t] != -1);
}

inline int dfs(int x, int totFlow) {
    if (x == t || totFlow ==0) return totFlow;
    int ans = totFlow;
    for (int i = head[x]; i != -1; i = e[i].nxt) {
        if (deep[e[i].to] == deep[x] + 1 && e[i].val) {
            int flow = dfs(e[i].to, min(totFlow,e[i].val));
            e[i].val -= flow;
            e[i ^ 1].val += flow;
            totFlow -= flow;
            if (totFlow == 0) return ans;
        }
    }
    return ans - totFlow;
}

inline void dinic() {
    while (bfs()) {
        res += dfs(s, INF);
    }
}