Submission #1095471

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095471		stefanopulos	JJOOII 2 (JOI20_ho_t2)	C++17	100 / 100	8 ms	3108 KiB

ho_t2

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
 
using namespace std;
using namespace __gnu_pbds;
 
typedef long long ll;
typedef long double ldb;
 
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ldb,ldb> pdd;
 
#define ff(i,a,b) for(int i = a; i <= b; i++)
#define fb(i,b,a) for(int i = b; i >= a; i--)
#define trav(a,x) for (auto& a : x)
 
#define sz(a) (int)(a).size()
#define pb push_back
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k)  print the k-th smallest number in os(0-based)

const int mod = 1000000007;
const int inf = 1e9 + 5;
const int mxN = 200005; 

int n, k;
string s;

queue<int> J, O, I;

int pref[mxN];
int sufi[mxN];

int f(char c){
    if(c == 'J')return 0;
    if(c == 'O')return 1;
    if(c == 'I')return 2;
    assert(false);
}

int main() {
    cin.tie(0)->sync_with_stdio(0);

    cin >> n >> k >> s; s = ' ' + s;   

    pref[0] = inf;
    ff(i,1,n){
        if(f(s[i]) == 0)J.push(i); 
        if(sz(J) > k)J.pop();

        pref[i] = pref[i - 1];
        if(sz(J) >= k){
            int l = J.front(); 
            int r = i;
            pref[i] = (r - l + 1) - k; 
        }   

    } 

    sufi[n + 1] = inf;
    fb(i,n,1){
        if(f(s[i]) == 2)I.push(i); 
        if(sz(I) > k)I.pop();

        sufi[i] = sufi[i + 1];
        if(sz(I) >= k){
            int l = i;
            int r = I.front(); 
            sufi[i] = (r - l + 1) - k; 
        }   

    }

    int rez = inf; // O
    ff(i,1,n){
        if(f(s[i]) == 1)O.push(i); 
        if(sz(O) > k)O.pop();

        if(sz(O) >= k){
            int l = O.front(); 
            int r = i;
            rez = min(rez, pref[l - 1] + sufi[r + 1] + (r - l + 1) - k);
        }        

    }

    cout << (rez == inf ? -1 : rez) << '\n';

    return 0;
}
/*
 
10 2
OJIJOIOIIJ

9 3
JJJOOOIII

9 1
IIIOOOJJJ

// probati bojenje sahovski
*/
 
 
 
 
 

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