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标签:algo   type   one   click   str   efi   bsp   from   网络   

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#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <algorithm>
using namespace std;

int read() {
    int x = 0, f = 1; char c = getchar();
    while(!isdigit(c)){ if(c == -) f = -1; c = getchar(); }
    while(isdigit(c)){ x = x * 10 + c - 0; c = getchar(); }
    return x * f;
}

#define maxn 1000010
#define maxm 8000010
#define oo 2147483647
#define LL long long

struct Edge {
    int from, to, flow;
    Edge() {}
    Edge(int _1, int _2, int _3): from(_1), to(_2), flow(_3) {}
} ;
struct Dinic {
    int n, m, s, t, head[maxn], nxt[maxm];
    Edge es[maxm];
    int vis[maxn], Q[maxn], hd, tl;
    int cur[maxn];
    
    void init() {
        m = 0; memset(head, -1, sizeof(head));
        return ;
    }
    void setn(int _n) { n = _n; return ; }
    
    void AddEdge(int a, int b, int c) {
        es[m] = Edge(a, b, c); nxt[m] = head[a]; head[a] = m++;
        es[m] = Edge(b, a, 0); nxt[m] = head[b]; head[b] = m++;
        return ;
    }
    
    bool BFS() {
        memset(vis, 0, sizeof(vis));
        vis[t] = 1;
        hd = tl = 0; Q[++tl] = t;
        while(hd < tl) {
            int u = Q[++hd];
            for(int i = head[u]; i != -1; i = nxt[i]) {
                Edge& e = es[i^1];
                if(!vis[e.from] && e.flow) {
                    vis[e.from] = vis[u] + 1;
                    Q[++tl] = e.from;
                }
            }
        }
        return vis[s] > 1;
    }
    int DFS(int u, int a) {
        if(u == t || !a) return a;
        int flow = 0, f;
        for(int& i = cur[u]; i != -1; i = nxt[i]) {
            Edge& e = es[i];
            if(vis[e.to] == vis[u] - 1 && (f = DFS(e.to, min(a, e.flow)))) {
                flow += f; a -= f;
                e.flow -= f; es[i^1].flow += f;
                if(!a) return flow;
            }
        }
        return flow;
    }
    LL MaxFlow(int _s, int _t) {
        s = _s; t = _t;
        LL flow = 0;
        while(BFS()) {
            for(int i = 1; i <= n; i++) cur[i] = head[i];
            flow += DFS(s, oo);
        }
        return flow;
    }
} sol;

int main() {
    int n = read(), m = read(), s = read(), t = read();
    
    sol.init(); sol.setn(n);
    for(int i = 1; i <= m; i++) {
        int a = read(), b = read(), c = read();
        sol.AddEdge(a, b, c);
    }
    
    printf("%lld\n", sol.MaxFlow(s, t));
    
    return 0;
}
View Code
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#include <bits/stdc++.h>
using namespace std;
#define rep(i, s, t) for(int i = (s), mi = (t); i <= mi; i++)
#define dwn(i, s, t) for(int i = (s), mi = (t); i >= mi; i--)

int read() {
    int x = 0, f = 1; char c = getchar();
    while(!isdigit(c)) { if(c == -) f = -1; c = getchar(); }
    while(isdigit(c)) { x = x * 10 + c - 0; c = getchar(); }
    return x * f;
}

#define maxn 500010
#define maxm 500010
#define oo 2147483647

namespace ZKW {
    struct Edge {
        int from, to, flow, cost;
        Edge() {}
        Edge(int _1, int _2, int _3, int _4): from(_1), to(_2), flow(_3), cost(_4) {}
    } es[maxm];
    int n, m, s, t, ans, cost, head[maxn], nxt[maxm];
    int Q[maxn], hd, tl, d[maxn];
    bool inq[maxn];
    bool vis[maxn];
    
    void init() {
        ans = 0;
        m = 0; memset(head, -1, sizeof(head));
        return ;
    }
    void clearFlow() {
        for(int i = 0; i < m; i += 2) es[i].flow += es[i^1].flow, es[i^1].flow = 0;
        return ;
    }
    
    void AddEdge(int a, int b, int c, int d) {
        es[m] = Edge(a, b, c, d); nxt[m] = head[a]; head[a] = m++;
        es[m] = Edge(b, a, 0, -d); nxt[m] = head[b]; head[b] = m++;
        return ;
    }
    
    int Nxt(int x) { return (x + 1) % maxn; }
    bool BFS() {
        rep(i, 1, n) d[i] = oo;
        d[t] = 0;
        hd = tl = 0; Q[tl = Nxt(tl)] = t; inq[t] = 1;
        while(hd != tl) {
            int u = Q[hd = Nxt(hd)]; inq[u] = 0;
            for(int i = head[u]; i != -1; i = nxt[i]) {
                Edge &e = es[i^1];
                if(e.flow && d[e.from] > d[u] + e.cost) {
                    d[e.from] = d[u] + e.cost;
                    if(!inq[e.from]) inq[e.from] = 1, Q[tl = Nxt(tl)] = e.from;
                }
            }
        }
        if(d[s] == oo) return 0;
        cost = d[s];
        return 1;
    }
    
    int DFS(int u, int a) {
        if(u == t || !a) return ans += cost * a, a;
        if(vis[u]) return 0;
        vis[u] = 1;
        int flow = 0, f;
        for(int i = head[u]; i != -1; i = nxt[i]) {
            Edge &e = es[i];
            if(d[e.to] == d[u] - e.cost && (f = DFS(e.to, min(a, e.flow)))) {
                flow += f; a -= f;
                e.flow -= f; es[i^1]. flow += f;
                if(!a) return flow;
            }
        }
        return flow;
    }
    
    int MaxFlow(int _s, int _t) {
        s = _s; t = _t;
        int flow = 0, f;
        while(BFS())
            do {
                memset(vis, 0, sizeof(int) * (n + 1));
                f = DFS(s, oo);
                flow += f;
            } while(f);
        return flow;
    }
}
using ZKW::AddEdge;

int main() {
    int n = read(), m = read();
    ZKW::init(); ZKW::n = n;
    rep(i, 1, m) {
        int a = read(), b = read(), c = read(), d = read();
        AddEdge(a, b, c, d);
    }
    printf("%d ", ZKW::MaxFlow(1, n));
    printf("%d\n", ZKW::ans);
    
    return 0;
}
View Code

 

网络流

标签:algo   type   one   click   str   efi   bsp   from   网络   

原文地址:https://www.cnblogs.com/Kong-Ruo/p/10247107.html

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