POJ 1149 PIGS 最大流

sap+gap优化

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
#define maxn 105
#define inf 1000000000

int min(int a, int b)
{
    return a < b ? a : b;
}
struct E
{
    int v, next, c;
}edge[10003 << 1];

int head[maxn], tot;
int n, m;

void add(int s, int t, int c)
{
    edge[tot].v = t;
    edge[tot].c = c;
    edge[tot].next = head[s];
    head[s] = tot++;
    edge[tot].v = s;
    edge[tot].c = 0;
    edge[tot].next = head[t];
    head[t] = tot++;
}

void init()
{
    tot = 0;
    memset(head, -1, sizeof(head));
}

int gap[maxn], dis[maxn], pre[maxn], cur[maxn];

int sap(int s, int t, int vs)
{
    memset(gap, 0, sizeof(gap));
    memset(dis, 0, sizeof(dis));
    gap[0] = vs;
    memcpy(cur, head, sizeof(head));
    int i, u = pre[s] = s, maxf = 0, aug = inf, v;
    while(dis[s] < vs)
    {
loop:   for(i = head[u]; i != -1; i = edge[i].next)
        {
            v = edge[i].v;
            if(edge[i].c > 0 && dis[u] == dis[v] + 1)
            {
                aug = min(aug, edge[i].c);
                pre[v] = u;
                cur[u] = i;
                u = v;
                if(u == t)
                {
                    for(u = pre[u]; v != s; v = u, u = pre[u])
                    {
                        edge[cur[u]].c -= aug;
                        edge[cur[u]^1].c += aug;
                    }
                    maxf += aug;
                    aug = inf;
                }
                goto loop;
            }
        }
        int min_d = vs;
        for(i = head[u]; i != -1; i = edge[i].next)
        {
            v = edge[i].v;
            if(edge[i].c > 0 && dis[v] < min_d)
                min_d = dis[v];
        }
        if( !(--gap[dis[u]])) break;
        ++gap[dis[u] = min_d + 1];
        u = pre[u];
    }
    return maxf;
}

int house[1005], last[1005];
int main()
{
    int i, j, k;
    while( ~scanf("%d%d", &m, &n))
    {
        int S = 0, T = n+1;
        init();
        for(i = 1; i <= m; i++)
            scanf("%d", &house[i]);
        memset(last, -1, sizeof(last));
        for(i = 1; i <= n; i++)
        {
            int tmp;
            scanf("%d", &tmp);
            while(tmp--)
            {
                scanf("%d", &k);
                if(last[k] == -1)
                    add(S, i, house[k]);
                else
                    add(last[k], i, inf);
                last[k] = i;
            }
            scanf("%d", &tmp);
            add(i, T, tmp);
        }
        printf("%d\n", sap(S, T, n+2));
    }
    return 0;
}