hdu2883 最大流，判断满流 优化的SAP算法

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

const int N=2000,M=1000000, INF=0x3f3f3f3f;
struct node
{
    int to,next,w;
}edge[M];
int head[N],numh[N],h[N],cure[N],pre[N];
//numh:GAP优化的统计高度数量数组; h：距离标号数组; cure:当前弧
int ans,tot;
void SAP(int s, int e,int n)
{
    int flow,u,tmp,neck,i;
    ans=0;
    for(i=1;i<=n;i++)
        cure[i]=head[i];
    numh[0]=n;
    u=s;
    while(h[s]<n)
    {
        if(u==e)
        {
            flow =INF;
            for(i=s;i!=e;i=edge[cure[i]].to)
            {
                if(flow>edge[cure[i]].w)
                {
                    neck=i;
                    flow =edge[cure[i]].w;
                }
            }
            for(i=s;i!=e;i=edge[cure[i]].to)
            {
                tmp=cure[i];
                edge[tmp].w-=flow;
                edge[tmp^1].w+=flow;
            }
            ans+=flow;
            u=neck;
        }
        for(i=cure[u];i!=-1;i=edge[i].next)
            if(edge[i].w && h[u]==h[edge[i].to]+1) break;
        if(i!=-1) {cure[u]=i;pre[edge[i].to]=u;u=edge[i].to;}
        else
        {
            if(0==--numh[h[u]]) break; //GAP优化
            cure[u]=head[u];
            for(tmp=n,i=head[u];i!=-1;i=edge[i].next)
                if(edge[i].w) tmp=min(tmp, h[edge[i].to]);
            h[u]=tmp+1;
            ++numh[h[u]];
            if(u!=s) u=pre[u];
        }
    }
}
void init()
{
    tot=0;
    memset(head,-1,sizeof(head));
    memset(pre,-1,sizeof(pre));
    memset(h,0,sizeof(h));
    memset(numh,0,sizeof(numh));

}
void addedge(int i,int j,int w)
{
    edge[tot].to=j;edge[tot].w=w;edge[tot].next=head[i];head[i]=tot++;
    edge[tot].to=i;edge[tot].w=0;edge[tot].next=head[j];head[j]=tot++;
}
int T[N],st[N],ed[N];
int main()
{
    //freopen("test.txt","r",stdin);
    int n,m,i,j,k,a,b,c,sum,s,t;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        init();
        sum=0;s=n+1;
        k=0;
        for(i=1;i<=n;i++)
        {
            scanf("%d%d%d%d",&st[i],&b,&ed[i],&t);
            sum+=b*t;
            addedge(s,i,b*t);
            T[k++]=st[i];
            T[k++]=ed[i];
        }
        sort(T,T+k);
        j=0;
        for(i=1;i<k;i++)
            if(T[j]!=T[i]) T[++j]=T[i];
        k=s+1+j;
        for(i=1;i<=j;i++)
        {
            addedge(s+i,k,m*(T[i]-T[i-1]));
            for(t=1;t<=n;t++)
                if(st[t]<=T[i-1]&&ed[t]>=T[i]) addedge(t,i+s,INF);
        }
        SAP(s,k,k);
        if(ans==sum) printf("Yes\n");
        else printf("No\n");
    }
    return 0;
}