Submission #1129663

#	Time	Username	Problem	Language	Result	Execution time	Memory
1129663		am_aadvik	JJOOII 2 (JOI20_ho_t2)	C++17	100 / 100	32 ms	3876 KiB

ho_t2

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

int main()
{
	int n, k; cin >> n >> k;
	string s, l = "JOI"; cin >> s;
	vector<vector<int>> pre(3, vector<int>(n, 0));
	for (int i = 0; i < 3; ++i) {
		int x = n - 1, y = n - 1, cnt = 0, cur = -1;
		while (((x >= 0) && (y >= 0))) {
			while ((x >= 0) && (cnt < k)) {
				if (s[x] == l[i]) cnt++;
				if (cnt == k) break;
				pre[i][x] = cur; --x;
			}
			if (x < 0) break;
			for (; y >= x; --y) if (s[y] == l[i]) break;
			cur = y, y--, cnt--, pre[i][x--] = cur;
		}
	}

	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; ++i) {
				j = pre[i][j];
				if ((j == -1) || (j > e)) { 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