Submission #64332276

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Source Code Expand

#include <iostream>
#include <vector>
#include <cstring>
using namespace std;
#define MaxN 400005
int n, a[MaxN], l[MaxN], r[MaxN], ans;

void check(int a, int b) {
	if (l[b] + 1 == r[b]) return ;
	if (abs(l[a]-l[b])==1 && abs(r[a]-r[b])==1) ans++;
}

void work() {
	ans = 0;
	cin >> n;
	for(int i = 1; i <= 2*n; i++) {
		cin >> a[i];
		if (l[a[i]] == 0) l[a[i]] = i;
		else r[a[i]] = i;
	}
	for(int i = 1; i <= n; i++) { // 数字i是否能构造答案
		if (l[i] + 1 == r[i]) continue;
		if (l[a[l[i]+1]] == l[i]+1) check(i, a[l[i]+1]);
	}
	// for(int i = 1; i <= n; i++) {
	// 	if (l[i] + 1 == r[i]) continue;
	// 	for(int j = i+1; j <= n; j++) {
	// 		if (l[j] + 1 == r[j]) continue;
	// 		check(i, j);
	// 	}
	// }
	cout << ans << endl;
	for(int i = 1; i <= n; i++) l[i] = 0;
}

int main()
{
	int T;
	cin >> T;
	while (T--) {
		work();
	}
	return 0;
}

Submission Info

Judge Result