Submission #1476883

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Source Code Expand

#include "bits/stdc++.h"
using namespace std;
#ifdef _DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

//#define int long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(c) begin(c),end(c)
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; }

signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N, K; cin >> N >> K;
	vector<bool> a(N);
	vector<int> A(K); rep(i, 0, K) {
		cin >> A[i];
		A[i]--;
		a[A[i]] = true;
	}
	vector<string> S(N); rep(i, 0, N) {
		cin >> S[i];
	}
	auto f = [&](int x) {
		bool ok = true;
		string s;
		rep(i, 0, N) {
			if (a[i]) {
				if (S[i].size() < x) {
					return true;
				}
				if (s.size() == 0 && x != 0)
					s = S[i].substr(0, x);
			}
		}
		rep(i, 0, N) {
			if (a[i]) {
				if (S[i].substr(0, x) != s) {
					ok = false;
					break;
				}
			}
			else {
				if (S[i].size() < x)continue;
				if (S[i].substr(0, x) == s) {
					ok = false;
					break;
				}
			}
		}
		return ok;
	};
	auto binarySearch = [&](int ng, int ok) {
		if (f(ng))return ng;
		while (ng + 1 < ok) {
			int m = (ng + ok) / 2;
			if (f(m))
				ok = m;
			else
				ng = m;
		}
		return ok;
	};
	int c = binarySearch(0, 100010);
	rep(i, 0, N) {
		if (a[i] && S[i].size() < c) {
			cout << -1 << endl;
			return 0;
		}
	}
	cout << S[A[0]].substr(0, c) << endl;
	return 0;
}

Submission Info

Judge Result