Submission #516974

#	Time	Username	Problem	Language	Result	Execution time	Memory
516974		kevinxiehk	JJOOII 2 (JOI20_ho_t2)	C++17	100 / 100	4 ms	3488 KiB

ho_t2

#include <bits/stdc++.h>
#define mp make_pair
#define pb emplace_back
#define fi first
#define se second
#define int long long
#define inf 1e18
#define ick cout<<"ickbmi32.9\n"
using namespace std;
bool isprime(int k) {
    for(int i = 2; i <= sqrt(k); i++) if(k % i == 0) return false; 
    return true;    
}
int bm(int a, int b, int mod) {
    if(b == 0) return 1; 
    int t = bm(a, b / 2, mod); 
    t = t * t % mod; 
    return (b % 2 == 1 ? t * a % mod : t);
}
int inv(int a, int mod) {return bm(a, mod - 2, mod);}
int n, k;
string s;
int jpos[200005], ipos[200005], ops[200005];// 1-based!!!
signed main(){
    ios_base::sync_with_stdio(false); 
    cin.tie(0); cout.tie(0);
    cin >> n >> k >> s; k--;
    s = "_" + s;
    int jcnt = 0, icnt = 0;
    for(int i = 1; i <= n; i++) {
        if(s[i] == 'J') jpos[jcnt++] = i;
        else if(s[i] == 'I') ipos[icnt++] = i;
        else ops[i]++;
        ops[i] += ops[i - 1];
    }
    int ans = inf;
    int rpt = 0;
    for(int i = 0; i < jcnt - k; i++) {
        while(rpt + k < icnt && ops[ipos[rpt]] - ops[jpos[i + k]] <= k) rpt++;
        if(rpt + k >= icnt) break;
        ans = min(ans, ipos[rpt + k] - jpos[i] - 2 - 3 * k);
    }
    if(ans == inf) ans = -1;
    cout << ans << '\n';
    return 0;
}

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