Submission #909666

#	Time	Username	Problem	Language	Result	Execution time	Memory
909666		schzeey	Watching (JOI13_watching)	C++14	100 / 100	572 ms	30460 KiB

watching

#include <bits/stdc++.h>
using namespace std;
#define int long long
int n, a, b;
vector <int> arr;
bool check(int ans){
    vector<vector<int>> dp(n+1, vector<int>(a+1, 0));
    arr[0] = ans*-1;
    for (int i = 1; i <= n; ++i){
        int pa = i, pb = i;
        do pa--; while(pa != 0 && arr[i]-arr[pa] < ans);
        do pb--; while(pb != 0 && arr[i]-arr[pb] < 2*ans);
        /*int pa = 0, pb = 0;
        while (pa+1 < i && arr[i]-arr[pa+1] >= ans) pa++;
        while (pb+1 < i && arr[i]-arr[pb+1] >= 2*ans) pb++;*/
        for (int j = 0; j < a+1; ++j){
            if (j == 0) dp[i][j] = dp[pb][j]+1;
            else dp[i][j] = min(dp[pb][j]+1, dp[pa][j-1]);
        }
    }
    return *min_element(dp[n].begin(), dp[n].end()) <= b;
}

int32_t main(){
    cin >> n >> a >> b;
    arr.resize(n+1);
    for (int i = 1; i <= n; ++i) cin >> arr[i];
    if (a+b >= n) return cout<<1, 0;
    sort(arr.begin(), arr.end());
    //for (auto e: arr) cout << e << " ";
    int lf = 0, ri = 1e9+128;
    while (lf <= ri){
        int mid = (lf+ri)/2;
        //cout << mid << " ";
        if (check(mid)) ri = mid-1;
        else lf = mid+1;
    }
    cout << lf;
}

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50