最小费用最大流 模板

#include<cstdio>#include<iostream>#include<algorithm>#include<cstring>#define maxn 1010#define maxm 1010101#define Inf 2147483647using namespace std;struct Edge{int u, v, cap, flow, cost;int next;}e[maxm];int n, m, s, t;int flow = 0, cost = 0;int fi[maxn], ecnt;int inq[maxn], p[maxn];//p：上一条边 int d[maxn];//spfa int a[maxn];//可改进量 void add_edge(int u, int v, int cap, int cost) {ecnt++;e[ecnt] = (Edge){u, v, cap, 0, cost, fi[u]};fi[u] = ecnt;}bool spfa(int s, int t) {for(int i = 1; i <= n; i++)d[i] = Inf;memset(inq, 0, sizeof(inq));d[s] = 0, inq[s] = 1, p[s] = 0, a[s] = Inf;int q[maxn], head = 0, tail = 1;q[head] = s;while(head < tail) {int u = q[head++];inq[u] = 0;for(int i = fi[u]; i != -1; i = e[i].next)if(e[i].cap > e[i].flow && d[e[i].v] > d[u] + e[i].cost) {d[e[i].v] = d[u] + e[i].cost;p[e[i].v] = i;a[e[i].v] = min(a[u], e[i].cap - e[i].flow);if(!inq[e[i].v]) {q[tail++] = e[i].v, inq[e[i].v] = 1;}}}if(d[t] == Inf) return false;flow += a[t], cost += d[t]*a[t];int u = t;while(u != s) {e[p[u]].flow += a[t];e[p[u]^1].flow -= a[t];u = e[p[u]].u;}return true;}int main() {memset(fi, -1, sizeof(fi));scanf("%d%d", &n, &m);s = 1, t = n;for(int i = 1; i <= m; i++) {int u, v, cap, cost;scanf("%d%d%d%d", &u, &v, &cap, &cost);add_edge(u, v, cap, cost);add_edge(v, u, 0, -cost);}while(spfa(s, t));printf("%d", cost);return 0;}

果然还是自己写的模板看起来舒服==