Submission #422874

#	Time	Username	Problem	Language	Result	Execution time	Memory
422874		abdzag	Necklace (Subtask 1-3) (BOI19_necklace1)	C++17	85 / 85	409 ms	71184 KiB

necklace

#include<bits/stdc++.h>
#include<unordered_map>
#define rep(i,a,b) for(int i=int(a);i<int(b);i++)
#define rrep(i,a,b) for(int i=int(a);i>int(b);i--)
#define trav(a,v) for(auto& a: v)
#define sz(v) v.size()
#define all(v) v.begin(),v.end()
#define vi vector<int>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const long long inf = 1e15;

int main() {
	cin.sync_with_stdio(false);
	string a, b;
	cin >> a >> b;
	ll ans = 0;
	ll pos1, pos2;
	vector<vector<ll>> v(3001, vector<ll>(3001));
	rep(i, 0, b.size()) {
		ll counter = 0;
		rep(j, 1, a.size()+1) {
			if (b[i+counter] == a[j-1])v[i][j] = ++counter;
			else {
				while (b[i + counter] != a[j - 1] && counter)counter--;
				if (b[i + counter] == a[j - 1])v[i][j] = ++counter;
			}
		}
	}
	rep(i, 0, a.size()) {
		ll counter = 0;
		rep(j, 1, b.size() + 1) {
			if (a[i + counter] == b[j-1])counter++;
			else {
				while (a[i + counter] != b[j - 1] && counter)counter--;
				if (a[i + counter] == b[j - 1])++counter;
			}
			if (ans < counter + v[j][i]) {
				ans = counter + v[j][i];
				pos1 = i - v[j][i];
				pos2 = j - counter;
			}
		}
	}
	reverse(all(a));
	v.clear();
	v.resize(3001, vector<ll>(3001, 0));
	rep(i, 0, b.size()) {
		ll counter = 0;
		rep(j, 1, a.size() + 1) {
			if (b[i + counter] == a[j - 1])v[i][j] = ++counter;
			else {
				while (b[i + counter] != a[j - 1]&&counter)counter--;
				if (b[i + counter] == a[j - 1])v[i][j] = ++counter;
			}
		}
	}
	rep(i, 0, a.size()) {
		ll counter = 0;
		rep(j, 1, b.size() + 1) {
			if (a[i + counter] == b[j - 1])counter++;
			else {
				while (a[i + counter] != b[j - 1] && counter)counter--;
				if (a[i + counter] == b[j - 1])counter++;
			}
			if (ans < counter + v[j][i]) {
				ans = counter + v[j][i];
				pos1 = a.size()-i - counter;
				pos2 = j - counter;
			}
		}
	}
	cout << ans << endl;
	if (ans)cout << pos1 << " " << pos2;
	return 0;
}

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