题解 | 宝石手串

#include<bits/stdc++.h>
using namespace std;
#define inf 0x3f3f3f3f

void solve() {
	string s;
	int n;
	cin >> n >> s;
	vector<int> v[30];
	for (int i = 0; i < n; i++) v[s[i] - 'a'].push_back(i);
	int ans = inf;
	for (int i = 0; i < 26; i++) {
		if (v[i].size() < 2) continue;
		for (int j = 1; j < v[i].size(); j++) ans = min(ans, v[i][j] - v[i][j - 1] - 1);
//		cout << i << " " << ans << endl;
		int x = v[i][0] - v[i][v[i].size() - 1] - 1 + n;
		ans = min(ans, x);
	}
	if (ans == inf) cout << - 1 << endl;
	else cout << ans << endl;
}

int main() {
	int _ = 1;
	cin >> _;
	while (_--) solve();
	return 0;
}