题意：给你星星的坐标（Y递增，若Y相等则X递增），每个星星有个等级，规定它的等级是它左下方的星星个数，输出所有星星的等级

思路：树状数组

#include 
  
   
#include 
   
     #include 
    
      #include 
     
       using namespace std; const int MAXN = 32010; int n,lev[MAXN],c[MAXN]; void add(int x,int d){ while (x < MAXN) c[x] += d,x += x&-x; } int sum(int x){ int res = 0; while (x > 0) res += c[x],x -= x&-x; return res; } int main(){ int x,y; while (scanf("%d",&n) != EOF){ memset(lev,0,sizeof(lev)); memset(c,0,sizeof(c)); for (int i = 0; i < n; i++){ scanf("%d%d",&x,&y); x++; lev[sum(x)]++; add(x,1); } for (int i = 0; i < n; i++) printf("%d\n",lev[i]); } return 0; }