最大流(SAP + GAP邻接表) 手敲模板

SAP + GAP 邻接矩阵：https://blog.youkuaiyun.com/Adolphrocs/article/details/84779661

dinic 邻接表：https://blog.youkuaiyun.com/Adolphrocs/article/details/84779691

dinic 邻接矩阵： https://blog.youkuaiyun.com/Adolphrocs/article/details/84779732

#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int MAXN = 5010;
const int MAXM = 200010;
const int MAXN_INT = (1 << 29);

struct Edge{
    int v, w, nxt;
};

bool isFind;
int head[MAXN];
Edge edge[MAXM];
int dis[MAXN], gap[MAXN];
int n, m, ecnt, aug, maxFlow;


void init(){
    ecnt = maxFlow = 0;
    memset(gap, 0, sizeof(gap));
    memset(dis, 0, sizeof(dis));
    memset(edge, 0, sizeof(edge));
    memset(head, -1, sizeof(head));
    gap[0] = n;
}

void addEdge(int u, int v, int w){
    edge[ecnt].v = v;
    edge[ecnt].w = w;
    edge[ecnt].nxt = head[u];
    head[u] = ecnt++;
}

void Find(int s){
    int dx, augc, minDis;
    if(s == n){
        isFind = true;
        maxFlow += aug;
        return;
    }

    augc = aug;
    minDis = n - 1;
    for(int i = head[s]; i + 1; i = edge[i].nxt){
        if(edge[i].w > 0){
            if(dis[s] == dis[edge[i].v] + 1){
                aug = min(aug, edge[i].w);
                Find(edge[i].v);
                if(dis[1] >= n) return;
                if(isFind){
                    dx = i;
                    break;
                }
                aug = augc;
            }
            minDis = min(minDis, dis[edge[i].v]);
        }
    }
    if(!isFind){
        gap[dis[s]]--;
        if(gap[dis[s]] == 0) dis[1] = n;
        dis[s] = minDis + 1;
        gap[dis[s]]++;
    }else{
        edge[dx].w -= aug;
        edge[dx ^ 1].w += aug;
    }
}

int main(){
    while(scanf("%d%d", &n, &m) != EOF){
        init();
        int u, v, w;
        for(int i = 0; i < m; i++){
            scanf("%d%d%d", &u, &v, &w);
            addEdge(u, v, w);
            addEdge(v, u, 0);
        }

        while(dis[1] < n){
            isFind = 0;
            aug = MAXN_INT;
            Find(1);
        }
        cout << maxFlow << endl;
    }
    return 0;
}