2012 成都网络赛

标签：acm

Control

Input

Output

Sample Input

5 6
5 3
5
2
3
4
12
1 5
5 4
2 3
2 4
4 3
2 1

Sample Output

3

网络流： 点有权值费用，拆点建边。

#include <cstdio>
#include <queue>
#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;
typedef int MyType;
const int INF = 0x3F3F3F3F;
const int MAXN = 510;
const int MAXE = 100000 + 10;

struct Edge { int to, next; MyType cap; };
Edge es[MAXE];
int head[MAXN], cur[MAXN], level[MAXN], que[MAXN];
int n, m, src, des, cnt;

void add( int u, int v, MyType c ) {
    es[cnt].to = v; es[cnt].cap = c; es[cnt].next = head[u]; head[u] = cnt++;
    es[cnt].to = u; es[cnt].cap = 0; es[cnt].next = head[v]; head[v] = cnt++;
    return ;
}

bool bfs() {
    int mf, me;
    memset( level, 0, sizeof( level ) );
    mf = me = 0;
    que[me++] = src;
    level[src] = 1;
    while( mf < me ) {
        int u = que[mf++];
        for( int i = head[u]; ~i; i = es[i].next ) {
            int v = es[i].to;
            if( level[v] == 0 && es[i].cap > 0 ) {
                level[v] = level[u] + 1;
                que[me++] = v;
            }
        }
    }
    return ( level[des] != 0 );
}

int dfs( int u, int f ) {
    if( u == des || f == 0 ) return f;
    int flow = 0;
    for( int &i = cur[u]; ~i; i = es[i].next ) {
        Edge &e = es[i];
        if( e.cap > 0 && level[e.to] == level[u] + 1 ) {
            int d = dfs( e.to, min( f, e.cap ) );
            if( d > 0 ) {
                e.cap -= d;
                es[i ^ 1].cap += d;
                flow += d;
                f -= d;
                if( f == 0 ) break;
            } else level[e.to] = -1;
        }
    }
    return flow;
}

MyType dinic() {
    MyType ret = 0;
    while( bfs() ) {
        for( int i = 0; i <= 500; ++i ) {
            cur[i] = head[i];
        }
        ret += dfs( src, INF );
    }
    return ret;
}

int main()
{
    int a, b;
    while(~scanf("%d%d%d%d", &n, &m, &src, &des))
    {
        memset(head, -1, sizeof head);
        cnt = 0;
        int tt;
        des += 200;
        for( int i = 1; i <= n; ++i ) {
            scanf( "%d", &tt );
            add( i, i + 200, tt );
        }
        for( int i = 1; i <= m; ++i ) {
            scanf( "%d%d", &a, &b );
            add( a + 200, b, INF );
            add( b + 200, a, INF );
        }
        int ans = dinic();
        printf( "%d\n", ans );
    }
}

2012 成都网络赛

标签：acm

原文地址：http://blog.csdn.net/dojintian/article/details/47982469