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Submission #355795

# Submission time Handle Problem Language Result Execution time Memory
355795 2021-01-23T03:20:05 Z eyangch Watching (JOI13_watching) C++17
100 / 100
 249 ms 16108 KB 
#include <bits/stdc++.h>

using namespace std;

int N, P, Q;
int a[100000];
int dp[2001][2001]; // [num of events][large cameras]
int jmps[2001], jmpl[2001];

bool works(int mid){
    fill(dp[0], dp[N]+Q+1, 1e9);
    fill(dp[0], dp[0]+Q+1, 0);
    iota(jmps, jmps+N+1, -1);
    iota(jmpl, jmpl+N+1, -1);
    for(int i = N-1; i >= 0; i--){
        int idxs = upper_bound(a, a+N, a[i]-mid) - a - 1;
        int idxl = upper_bound(a, a+N, a[i]-2*mid) - a - 1;
        jmps[i] = idxs;
        jmpl[i] = idxl;
    }
    for(int i = 1; i <= N; i++){
        int pvs = jmps[i-1]+1, pvl = jmpl[i-1]+1;
        dp[i][0] = dp[pvs][0] + 1;
        for(int j = 1; j <= Q; j++){
            dp[i][j] = min(dp[pvl][j-1], dp[pvs][j] + 1);
        }
    }
    return (dp[N][Q] <= P);
}

int32_t main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> N >> P >> Q;
    if(P+Q >= N){
        cout << 1 << endl;
        return 0;
    }
    for(int i = 0; i < N; i++){
        cin >> a[i];
    }
    sort(a, a+N);
    int lo = 0, hi = 1e9, mid = 0;
    while(lo < hi){
        mid = (lo + hi) / 2;
        if(works(mid)){
            hi = mid-1;
        }else{
            lo = mid+1;
        }
    }
    while(works(mid)) mid--;
    while(!works(mid)) mid++;
    cout << mid << endl;
}

Subtask #1
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 1132 KB Output is correct
2 Correct 0 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 0 ms 364 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 4 ms 1132 KB Output is correct
8 Correct 6 ms 1132 KB Output is correct
9 Correct 4 ms 1132 KB Output is correct
10 Correct 4 ms 1132 KB Output is correct
11 Correct 4 ms 1132 KB Output is correct
12 Correct 4 ms 1132 KB Output is correct
13 Correct 4 ms 1132 KB Output is correct
14 Correct 6 ms 1132 KB Output is correct
15 Correct 5 ms 1132 KB Output is correct

Subtask #2
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 103 ms 15980 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 364 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 1 ms 384 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 101 ms 16000 KB Output is correct
8 Correct 166 ms 15980 KB Output is correct
9 Correct 120 ms 16108 KB Output is correct
10 Correct 115 ms 15980 KB Output is correct
11 Correct 249 ms 15980 KB Output is correct
12 Correct 183 ms 16108 KB Output is correct
13 Correct 118 ms 15980 KB Output is correct
14 Correct 104 ms 15980 KB Output is correct
15 Correct 106 ms 15980 KB Output is correct