Submission #1129604

#	Time	Username	Problem	Language	Result	Execution time	Memory
1129604		am_aadvik	JJOOII 2 (JOI20_ho_t2)	C++20	100 / 100	286 ms	64276 KiB

ho_t2

#include <iostream>
#include <vector>
#include<math.h>
using namespace std;

int nxtk(string& s, int i, vector<vector<vector<int>>>& pre, int j, int k) {
	int ans = j;
	for (int x = 0; x < 20; ++x)
		if ((k >> x) & 1) {
			ans = pre[i][x][ans] + 1;
			if (ans == -1) break;
		}
	return ans;
}

int main()
{
	int n, k; cin >> n >> k;
	string s, l = "JOI"; cin >> s; int lg = log2(n) + 1;
	vector<vector<vector<int>>> pre(3, vector<vector<int>>(20, vector<int>(n + 1, -2)));
	for (int i = 0; i < 3; ++i)
		for (int x = 0; x < lg; ++x)
			for (int j = n - 1; j >= 0; --j)
				if (x == 0) pre[i][x][j] = ((s[j] == l[i]) ? j : pre[i][x][j + 1]);
				else pre[i][x][j] = ((pre[i][x - 1][j] == -2) ? -2 : pre[i][x - 1][pre[i][x - 1][j] + 1]);

	int ans = n + 1;
	for (int f = 0; f < n; ++f) {
		int l = f + 2, r = n - 1;
		while (l <= r) {
			int e = (l + r) / 2, j = f;
			bool ok = 1;
			for (int i = 0; i < 3; j--, ++i) {
				j = nxtk(s, i, pre, j, k);
				if ((j == -1) || (j > (e + 1))) { ok = 0; break; }
			}
			if (ok) ans = min(ans, e - f + 1), r = e - 1;
			else l = e + 1;
		}
	}
	cout << ((ans == (n + 1)) ? -1 : ans - (3 * k)) << endl;
}

• Subtask 1: 1 / 1
• Subtask 2: 12 / 12
• Subtask 3: 87 / 87