pku 3067 Japan(变相逆序数)

#include <stdio.h>
#include <string.h>
#include <algorithm>

 

using namespace std;

#define MAXN 1010
#define MAXK 500010

struct HNode
{
    int x,y;
}highway[MAXK];
inline bool mycmp(const HNode &h1,const HNode &h2)
{return h1.x<h2.x;}

int c[MAXN];

inline int lowbit(int x)
{
    return x&(-x);
}
void update(int x,int delta)
{
    while(x<MAXN)
    {
        c[x]+=delta;
        x+=lowbit(x);
    }
}
int getSum(int x)
{
    int s=0;
    while(x>0)
    {
        s+=c[x];
        x-=lowbit(x);
    }
    return s;
}

int main()
{
    int T,cas,N,M,K,i;
    __int64 ans;
    scanf("%d",&T);
    highway[0].x=-1;
    for(cas=1;cas<=T;cas++)
    {
        scanf("%d %d %d",&N,&M,&K);
        for(i=1;i<=K;i++) scanf("%d %d",&highway[i].x,&highway[i].y);
        sort(highway+1,highway+K+1,mycmp);
        memset(c,0,sizeof(c));
        ans=0;
        for(i=1;i<=K;i++)
        {
            update(highway[i].y,1);
            ans+=(i-getSum(highway[i].y));
            if(highway[i].x == highway[i-1].x)
            {
                int j=i,t=0;
                while(j>=1 && highway[j].x==highway[j-1].x)
                {
                    j--;
                    if(highway[i].y < highway[j].y) t++;
                }
                ans -= t;
            }
        }
        printf("Test case %d: %I64d\n",cas,ans);
    }
    return 0;
}