codevs 1135 选择客栈

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 200500
using namespace std;
int n,k,p,pos[51][maxn],cnt[maxn],r[maxn],col[maxn],val[maxn],pre[maxn],regis=0;
long long ans=0;
int ask(int col,int poss)
{
    int l=1,r=cnt[col],ans=0;
    while (l<=r)
    {
        int mid=(l+r)>>1;
        if (pos[col][mid]<=poss) {ans=mid;l=mid+1;}
        else r=mid-1;
    }
    return pos[col][ans];
}
int main()
{
    scanf("%d%d%d",&n,&k,&p);
    for (int i=1;i<=n;i++)
        scanf("%d%d",&col[i],&val[i]);
    for (int i=1;i<=n;i++)
    {
        pos[col[i]][++cnt[col[i]]]=i;
        r[i]=cnt[col[i]];
        if (val[i]<=p) regis=i;
        pre[i]=regis;
    }
    for (int i=2;i<=n;i++)
    {
        if (r[i]==1) continue;
        if (pre[i]==i) ans+=r[i]-1;
        else 
            ans+=r[ask(col[i],pre[i])];
    }
    printf("%lld\n",ans);
    return 0;
}