codeforces #345 div 2 C. Watchmen (容斥)

 1#include <cstdio>
 2#include <cstring>
 3#include <iostream>
 4#include <algorithm>
 5#include <vector>
 6#include <queue>
 7#include <set>
 8#include <map>
 9#include <string>
10#include <cmath>
11#include <cstdlib>
12#include <ctime>
13#define fst first
14#define sec second
15#define lson l,m,rt<<1
16#define rson m+1,r,rt<<1|1
17#define ms(a,x) memset(a,x,sizeof(a))
18typedef long long LL;
19#define pi pair < int ,int >
20#define MP make_pair

1using namespace std;
2const double eps = 1E-8;
3const int dx4[4]={1,0,0,-1};
4const int dy4[4]={0,-1,1,0};
5const int inf = 0x3f3f3f3f;
6const int N=2E6+7;

1struct node
2{
3    int x,y;

1    bool operator < (node b)const
2    {
3	if (x==b.x) return y<b.y;
4	return x<b.x;
5    }
6}p[N];

 1bool cmp( node a,node b)
 2{
 3    return a.y<b.y;
 4}
 5LL cal( LL x)
 6{
 7    LL res = x*(x+1)/2;
 8    return res;
 9}
10int n;
11LL a,b,c;
12LL cnta,cntb,cntc;
13int main()
14{
15	#ifndef  ONLINE_JUDGE 
16	freopen("code/in.txt","r",stdin);
17  #endif

1	ios::sync_with_stdio(false);
2	cin>>n;
3	for ( int i = 1 ;i  <= n ; i++) cin>>p[i].x>>p[i].y;

 1	for ( int i = 1 ; i <= n-1 ; i++)
 2	{
 3	    if (p[i].x==p[i+1].x)
 4	    {
 5		cnta++;
 6	    }
 7	    else
 8	    {
 9		a+=cal(cnta);
10		cnta = 0 ;
11	    }
12	}
13	a +=cal(cnta);

 1	for ( int i = 1 ; i <= n-1 ; i++)
 2	{
 3	    if (p[i].x==p[i+1].x&&p[i].y==p[i+1].y)
 4	    {
 5		cntc++;
 6	    }
 7	    else
 8	    {
 9		c +=cal(cntc);
10		cntc = 0 ;
11	    }
12	}

 1	sort(p+1,p+n+1,cmp);
 2	for ( int i =  1 ; i  <= n-1 ; i ++)
 3	{
 4	    if (p[i].y==p[i+1].y)
 5	    {
 6		cntb++;
 7	    }
 8	    else
 9	    {
10		b +=cal(cntb);
11		cntb = 0 ;
12	    }
13	}
14	b +=cal(cntb);

1	LL ans=0LL;
2	ans = a+b-c;
3	cout<<ans<<endl;

1  #ifndef ONLINE_JUDGE  
2  fclose(stdin);
3  #endif
4    return 0;
5}