Submission #532137

#	Time	Username	Problem	Language	Result	Execution time	Memory
532137		scottchou	JJOOII 2 (JOI20_ho_t2)	C++17	100 / 100	8 ms	2176 KiB

ho_t2

#include<iostream>
#include<vector>
using namespace std;
vector<int> ipoint, opoint, jpoint;
int const N = 2e5 + 5;
int ov[N];
int inf = 1e9;
string s;
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n, k;
    cin >> n >> k;
    cin >> s;
    for(int i = 0; i < n; i++){
        if(s[i] == 'I'){
            ipoint.push_back(i);
        }else if(s[i] == 'O'){
            opoint.push_back(i);
        }else{
            jpoint.push_back(i);
        }
    }
    int now = ipoint.size() - 1, minn = inf;
    for(int i = opoint.size() - 1; i >= 0; i--){
        if(i < k - 1){
            ov[i] = inf;
            continue;
        }
        int p = opoint[i];
        while(now >= 0 && ipoint[now] > p){
            if(now + k - 1 <= ipoint.size() - 1){
                minn = min(minn, ipoint[now + k - 1] + 1 - k);
            }
            now--;
        }
        if(minn == inf){
            ov[i] = inf;
        }else{
            ov[i] = minn - opoint[i] - 1;
        }
    }
    int ans = inf;
    for(int i = 0; i < (int)jpoint.size() - k + 1; i++){
        int op = lower_bound(opoint.begin(), opoint.end(), jpoint[i + k - 1]) - opoint.begin();
        if(op + k - 1 >= opoint.size())
            continue;
        ans = min(ans, jpoint[i + k - 1] - jpoint[i] + 1 - k + opoint[op] - jpoint[i + k - 1] - 1 + ov[op + k - 1] + opoint[op + k - 1] - opoint[op] + 1 - k);
    }
    if(ans == inf){
        cout << -1 << '\n';
    }else{
        cout << ans << '\n';
    }
}

Compilation message (stderr)

ho_t2.cpp: In function 'int main()':
ho_t2.cpp:32:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |             if(now + k - 1 <= ipoint.size() - 1){
      |                ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
ho_t2.cpp:46:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |         if(op + k - 1 >= opoint.size())
      |            ~~~~~~~~~~~^~~~~~~~~~~~~~~~

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