제출 #594022

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
594022		stevancv	JJOOII 2 (JOI20_ho_t2)	C++14	0 / 100	1 ms	212 KiB

ho_t2

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 2e5 + 2;
const int mod = 1e9 + 7;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, k;
    cin >> n >> k;
    string s; cin >> s;
    vector<int> a(n);
    for (int i = 0; i < n; i++) {
        if (s[i] == 'J') a[i] = 0;
        if (s[i] == 'O') a[i] = 1;
        if (s[i] == 'I') a[i] = 2;
    }
    vector<vector<int>> pref(3, vector<int>(n));
    vector<vector<int>> pom(3, vector<int>(n + 1, -1));
    vector<vector<int>> wh(3, vector<int>(n + 1, -1));
    for (int i = 0; i < n; i++) {
        if (i > 0) {
            pref[0][i] += pref[0][i - 1];
        }
        if (a[i] != 0) continue;
        pom[0][++pref[0][i]] = i;
        if (pref[0][i] >= k) wh[0][i] = pom[0][pref[0][i] - k + 1];
    }
    for (int i = n - 1; i >= 0; i--) {
        if (i < n - 1) {
            pref[2][i] += pref[2][i + 1];
        }
        if (a[i] != 2) continue;
        pom[2][++pref[2][i]] = i;
        if (pref[2][i] >= k) wh[2][i] = pom[2][pref[2][i] - k + 1];
    }
    for (int i = 0; i < n; i++) {
        if (i > 0) pref[1][i] += pref[1][i - 1];
        if (a[i] == 1) pref[1][i]++;
    }
    auto Get = [&] (int l, int r) {
        if (l > r) return 0;
        int o = pref[1][r];
        if (l > 0) o -= pref[1][l - 1];
        return o;
    };
    if (pref[0].back() < k || pref[2][0] < k) {
        cout << -1 << en;
        return 0;
    }
    int l = 0;
    while (l < n && pref[0][l] < k) l++;
    int r = n - 1;
    while (r >= 0 && pref[2][r] < k) r--;
    int ans = 1e9;
    while (l < r) {
        if (Get(l + 1, r - 1) >= k && s[r] == 'I' && s[l] == 'J') smin(ans, wh[2][r] - wh[0][l] + 1 - 3 * k);
        else if (Get(l + 1, r - 1) < k) break;
        if (Get(l + 2, r - 1) > Get(l + 1, r - 2)) l++;
        else r--;
    }
    assert(ans >= 0);
    if (ans == 1e9) ans = -1;
    cout << ans << en;
    return 0;
}

• Subtask 1: 0 / 1
• Subtask 2: 0 / 12
• Subtask 3: 0 / 87