MinCost 费用流模板2

最新推荐文章于 2025-06-14 09:35:25 发布

转载最新推荐文章于 2025-06-14 09:35:25 发布 · 106 阅读

0 ·

CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/wangsouc/articles/3711220.html

本文深入探讨了一种比ZKW_flow更快的最小费用流算法实现，通过SPFA改进算法进行寻路，详细介绍了算法的结构、核心数据类型定义及关键函数实现，包括初始化、边的添加、最短路径搜索和最小费用流计算等步骤。

比 ZKW_flow 快

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<queue>
using namespace std;
#define maxn 1010
#define maxm 20010
const int inf = 0x3f3f3f3f;

struct Nod {
    int b, nxt;
    int cap, cst;
    void init(int b, int nxt, int cap, int cst) {
        this->b = b;
        this->nxt = nxt;
        this->cap = cap;
        this->cst = cst;
    }
};
struct MinCost {
    int E[maxn];
    int n;
    Nod buf[maxm * 2];
    int len;
    int p[maxn];
    void init(int n) {
        this->n = n;
        memset(E, 255, sizeof(E));
        len = 0;
    }
    void AddEdge(int a, int b, int cap, int cst) {
        buf[len].init(b, E[a], cap, cst);
        E[a] = len++;
        buf[len].init(a, E[b], 0, -cst);
        E[b] = len++;
    }
    bool spfa(int source, int sink) {
        static queue<int> q;
        static int d[maxn];
        memset(d, 63, sizeof(d));
        memset(p, 255, sizeof(p));
        d[source] = 0;
        q.push(source);
        int u, v;
        while (!q.empty()) {
            u = q.front();
            q.pop();
            for (int i = E[u]; i != -1; i = buf[i].nxt) {
                v = buf[i].b;
                if (buf[i].cap > 0 && d[u] + buf[i].cst < d[v]) {
                    d[v] = d[u] + buf[i].cst;
                    p[v] = i;
                    q.push(v);
                }
            }
        }
        return d[sink] != inf;
    }
    int Mincost(int source, int sink) {
        int minCost = 0, maxFlow = 0;//需要maxFlow的话,想办法返回
        while (spfa(source, sink)) {
            int neck = inf;
            for (int t = p[sink]; t != -1; t = p[buf[t ^ 1].b])//buf[t^壹].b是父节点
                neck = min(neck, buf[t].cap);
            maxFlow += neck;
            for (int t = p[sink]; t != -1; t = p[buf[t ^ 1].b]) {
                buf[t].cap -= neck;
                buf[t ^ 1].cap += neck;
                minCost += buf[t].cst * neck;
            }
        }
        return minCost;
    }
} MC;

View Code

转载于:https://www.cnblogs.com/wangsouc/articles/3711220.html