abc 258 G - Triangle（bitset）

G - Trianglehttps://atcoder.jp/contests/abc258/tasks/abc258_g直接用bitset存邻接矩阵，暴力一下就行

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <cstring>
#include <set>
#include <cmath>
#include <map>
#include <bitset>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
const int MN = 65005;
const int MAXN = 1e6 + 10;
const int INF = 0x3f3f3f3f;
#define IOS ios::sync_with_stdio(false)
#define lowbit(x) ((x)&(-x))
using P = pair<int, int>;


const int N = (int) 3e3 + 5;
//int s[5000][5000];
bitset<N> s[N];
int main() {
	int n;
	scanf("%d", &n);
	for (int i = 0; i < n; i++) {
		string str;
		cin >> str;
		reverse(str.begin(), str.end());
		s[i] = bitset<N>(str);
	}
	ll res = 0;
	for (int i = 0; i < n; i++) {
		for (int j = i + 1; j < n; j++) {
			if (s[i][j] == 1) {
				res += (s[i] & s[j]).count();
			}
		}
	}
	printf("%lld", res / 3);
	return 0;
}