HDU3917 最大权闭合图

来源：互联网发布：手机屏幕挂件软件编辑：程序博客网时间：2024/05/22 03:41
题目链接

http://acm.hdu.edu.cn/showproblem.php?pid=3917
题目就是最大权闭合图的模板题，，然后ek会t于是上网学了一发sap。
#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <vector>#include <queue>#define FF(i,NV) for(int i=0;i<NV;i++)using namespace std;const int M = 1000004;const int INF = 0x3f3f3f3f;int n, m;struct Node{    int c,pos,next;} E[M*4];struct Sap{    int NE,NV,tot;    int gap[M],dis[M],pre[M],head[M],cur[M];    void init()    {        NE=0,tot=0;        NV=m+1 + 1;        memset(head, -1, sizeof(head));    }    int sap(int s,int t)    {        memset(dis,0,sizeof(int)*(NV+1));        memset(gap,0,sizeof(int)*(NV+1));        FF(i,NV) cur[i] = head[i];        int u = pre[s] = s,maxflow = 0,aug =INF;        gap[0] = NV;        while(dis[s] < NV)        {    loop:            for(int &i = cur[u]; i != -1; i = E[i].next)            {                int v = E[i].pos;                if(E[i].c && dis[u] == dis[v] + 1)                {                    aug=min(aug,E[i].c);                    pre[v] = u;                    u = v;                    if(v == t)                    {                        maxflow += aug;                        for(u = pre[u]; v != s; v = u,u = pre[u])                        {                            E[cur[u]].c -= aug;                            E[cur[u]^1].c += aug;                        }                        aug =INF;                    }                    goto loop;                }            }            if( (--gap[dis[u]]) == 0)   break;            int mindis = NV;            for(int i = head[u]; i != -1 ; i = E[i].next)            {                int v = E[i].pos;                if(E[i].c && mindis > dis[v])                {                    cur[u] = i;                    mindis = dis[v];                }            }            gap[ dis[u] = mindis+1 ] ++;            u = pre[u];        }        return maxflow;    }    void AddEdge(int u,int v,int c )    {        E[NE].c = c;        E[NE].pos = v;        E[NE].next = head[u];        head[u] = NE++;        E[NE].c = 0;        E[NE].pos = u;        E[NE].next = head[v];        head[v] = NE++;    }}sek;int sum[100004];int zsum;int a[100004], b[100004], c[100004], d[100004];int main(){    while(scanf("%d%d", &n, &m), (n||m))    {        memset(sum, 0, sizeof(sum));        zsum = 0;        sek.init();        for(int i = 1;i <= m;i++)        {            int ls;            scanf("%d", &ls);            sek.AddEdge(0, i, ls);            zsum += ls;        }        int k;        scanf("%d", &k);        for(int i = 1;i <= k;i++)        {            int q, w, e, r;            scanf("%d%d%d%d", &q, &w, &e, &r);            a[i] = q, b[i] = w, c[i] = e, d[i] = r;            sum[c[i]] += r;        }        for(int i = 1;i <= k;i++)        {            for(int j = 1;j <= k;j++)            {                if(i != j)                {                    if(b[i] == a[j] && c[i] != c[j])                    {                        sek.AddEdge(c[i], c[j], INF);                    }                }            }        }        for(int i = 1;i <= m;i++)        {            sek.AddEdge(i, m + 1, sum[i]);        }        printf("%d\n", zsum - sek.sap(0, m + 1));    }    return 0;}
阅读全文
0 0