Strings of Impurity

link

不懂为什么都写平衡树，明明 set 就好了啊，思路跟平衡树差不多，实现起来较为简单。

int n, m, k;
int s[N];
string s1, s2;
int cnt[N];
vector<int> t;
set<int> p[N];
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
	cin >> s1 >> s2;
	n = s1.size(), m = s2.size();
	s1 = " " + s1, s2 = " " + s2;
	for(int i = 1; i <= n; i ++) {
		s[i] = s1[i] - 'a';
		cnt[s[i]] ++;
		p[s[i]].insert(i);
	}
	for(int i = 1; i <= m; i ++) {
		int x = s2[i] - 'a';
		if(cnt[x]) t.push_back(x);
	}
	if(t.size() != m) {
		cout << -1 << '\n';
		return 0;
	}
	int cur = 0, now = -1;
	k = 1;
	while(cur < t.size()) {
		auto it = p[t[cur]].lower_bound(now + 1);
		if(it == p[t[cur]].end()) {
			now = -1;
			k ++;
			continue;
		}
		cur ++;
		now = *it;
	}
	cout << (LL)(k - 1) * n + now << '\n';
    return 0;