【题解】组队 枚举 bzoj1071/洛谷 P4165 ——litble

#include<bits/stdc++.h>
using namespace std;
#define RI register int
const int N=5005;
int n,A,B,C,ans;
struct node{int v,h,s;}a[N],b[N];
bool cmp1(node x,node y) {return x.h<y.h;}
bool cmp2(node x,node y) {return x.s<y.s;}
int main()
{
    scanf("%d%d%d%d",&n,&A,&B,&C);
    for(RI i=1;i<=n;++i) {
        scanf("%d%d",&a[i].h,&a[i].v);
        a[i].s=A*a[i].h+B*a[i].v,b[i]=a[i];
    }
    sort(a+1,a+1+n,cmp1),sort(b+1,b+1+n,cmp2);
    for(RI i=1;i<=n;++i) {
        int minv=a[i].v,l=1,r=1,js=0;
        for(RI j=1;j<=n;++j) {
            int minh=a[j].h;
            while(r<=n&&b[r].s<=A*minh+B*minv+C) {
                if(b[r].v>=minv&&b[r].v<=C/B+minv) ++js;
                ++r;
            }
            while(l<=n&&a[l].h<minh) {
                if(a[l].v>=minv&&a[l].v<=C/B+minv) --js;
                ++l;
            }
            ans=max(ans,js);
        }
    }
    printf("%d\n",ans);
    return 0;
}