(树状数组) poj 3067

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cstdlib>
#include<cmath>
#include<algorithm>
using namespace std;
#define N 2010
int tt,n,m,k,c[N];
struct node
{
      int x,y,pos;
}e[N*N];
bool cmp(node a,node b)
{
      if(a.x!=b.x) return a.x<b.x;
      return a.y<b.y;
};
int lowbit(int x)
{
      return x&(-x);
}
void update(int pos,int m)
{
      while(pos<N)
      {
            c[pos]+=m;
            pos+=lowbit(pos);
      }
}
int sum(int x)
{
      int sum=0;
      while(x>0)
      {
            sum+=c[x];
            x-=lowbit(x);
      }
      return sum;
}
int main()
{
      int cas=1;
      scanf("%d",&tt);
      while(tt--)
      {
            long long  ans=0;
            memset(c,0,sizeof(c));
            scanf("%d%d%d",&n,&m,&k);
            for(int i=1;i<=k;i++)
                  scanf("%d%d",&e[i].x,&e[i].y);
            sort(e+1,e+1+k,cmp);
            for(int i=1;i<=k;i++)
            {
                  update(e[i].y,1);
                  ans+=i-sum(e[i].y);
            }
            printf("Test case %d: %I64d\n",cas,ans);
            cas++;
      }
      return 0;
}