oj.uz

Submission #361322

# Submission time Handle Problem Language Result Execution time Memory
361322 2021-01-29T09:54:10 Z mihai145 Watching (JOI13_watching) C++14
100 / 100
 510 ms 8684 KB 
//
// Created by mihai145 on 29.01.2021.
//

#include <iostream>
#include <algorithm>

using namespace std;

const int NMAX = 2000;
const int L = 1e9;

int N, P, Q;
int a[NMAX + 5];

int dp[NMAX + 5][NMAX + 5];

bool ok(int w) {
    for (int i = 0; i <= P; i++) {
        for (int j = 0; j <= Q; j++) {
            dp[i][j] = 0;
        }
    }

    for(int i = 0; i <= P; i++) {
        for(int j = 0; j <= Q; j++) {
            ///we place one more small camera
            if(dp[i][j] >= N) {
                dp[i + 1][j] = dp[i][j];
            } else {
                int startIndex = dp[i][j] + 1;
                int st = startIndex, dr = N, sol = startIndex;
                while(st <= dr) {
                    int mid = (st + dr) >> 1;
                    if(a[mid] - a[startIndex] < w) {
                        sol = mid;
                        st = mid + 1;
                    } else {
                        dr = mid - 1;
                    }
                }

                dp[i + 1][j] = max(dp[i + 1][j], sol);
            }

            ///we place one more big camera
            if(dp[i][j] >= N) {
                dp[i][j + 1] = dp[i][j];
            } else {
                int startIndex = dp[i][j] + 1;
                int st = startIndex, dr = N, sol = startIndex;
                while(st <= dr) {
                    int mid = (st + dr) >> 1;
                    if(a[mid] - a[startIndex] < 2 * w) {
                        sol = mid;
                        st = mid + 1;
                    } else {
                        dr = mid - 1;
                    }
                }

                dp[i][j + 1] = max(dp[i][j + 1], sol);
            }
        }
    }

    return (dp[P][Q] >= N);
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> N >> P >> Q;

    if (P + Q >= N) {
        cout << 1 << '\n';
        return 0;
    }

    ///P + Q < N

    for (int i = 1; i <= N; i++) {
        cin >> a[i];
    }
    sort(a + 1, a + N + 1);

    int st = 1, dr = L, sol = L;
    while (st <= dr) {
        int mid = (st + dr) >> 1;
        if (ok(mid)) {
            sol = mid;
            dr = mid - 1;
        } else {
            st = mid + 1;
        }
    }

    cout << sol << '\n';

    return 0;
}

Subtask #1
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 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 364 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 1 ms 364 KB Output is correct
8 Correct 1 ms 364 KB Output is correct
9 Correct 1 ms 364 KB Output is correct
10 Correct 1 ms 364 KB Output is correct
11 Correct 1 ms 620 KB Output is correct
12 Correct 2 ms 620 KB Output is correct
13 Correct 1 ms 364 KB Output is correct
14 Correct 1 ms 364 KB Output is correct
15 Correct 1 ms 364 KB Output is correct

Subtask #2
50.0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 364 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 384 KB Output is correct
5 Correct 1 ms 364 KB Output is correct
6 Correct 1 ms 364 KB Output is correct
7 Correct 1 ms 492 KB Output is correct
8 Correct 75 ms 1260 KB Output is correct
9 Correct 89 ms 3820 KB Output is correct
10 Correct 104 ms 8684 KB Output is correct
11 Correct 93 ms 1132 KB Output is correct
12 Correct 510 ms 8172 KB Output is correct
13 Correct 1 ms 364 KB Output is correct
14 Correct 1 ms 512 KB Output is correct
15 Correct 1 ms 492 KB Output is correct