Submission #556649

#	Time	Username	Problem	Language	Result	Execution time	Memory
556649		stefantaga	Necklace (Subtask 1-3) (BOI19_necklace1)	C++14	85 / 85	348 ms	492 KiB

necklace

#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

int p1[6002], p2[6002];

void fill_p(string s, int *p) {
	for (int i = 1; i < s.size(); i++) {
		int j = p[i - 1];
		while (j && s[i] != s[j]) j = p[j - 1];
		if (s[i] == s[j]) j++;
		p[i] = j;
	}
}

tuple<int, int, int> solve(string s, string t, bool rev) {
	int n = s.size(), m = t.size();
	tuple<int, int, int> ans = {0, 0, 0};
	for (int i = 0; i < n; i++) {
		string s1 = s.substr(0, i), s2 = s.substr(i, n - i);
		reverse(s1.begin(), s1.end());
		string t1 = t, t2 = t;
		reverse(t2.begin(), t2.end());
		fill_p(s1 + "#" + t1, p1), fill_p(s2 + "#" + t2, p2);
		for (int j = 1; j <= m; j++)
			ans = max(ans, {
				p1[i + j] + p2[n + m - i - j],
				i - p1[i + j],
				rev ? m - j - p2[n + m - i - j] : j - p1[i + j]
			});
	}
	return ans;
}

int main() {
	cin.tie(0)->sync_with_stdio(0);
	string s, t;
	cin >> s >> t;
	tuple<int, int, int> ans = solve(s, t, false);
	reverse(t.begin(), t.end());
	ans = max(ans, solve(s, t, true));
	cout << get<0>(ans) << '\n' << get<1>(ans) << ' ' << get<2>(ans);
	return 0;
}

Compilation message (stderr)

necklace.cpp: In function 'void fill_p(std::string, int*)':
necklace.cpp:8:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |  for (int i = 1; i < s.size(); i++) {
      |                  ~~^~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 20 / 20
• Subtask 3: 40 / 40