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Submission #213135

# Submission time Handle Problem Language Result Execution time Memory
213135 2020-03-25T04:11:48 Z tri Watching (JOI13_watching) C++14
0 / 100
 1000 ms 16256 KB 
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;

#define pb push_back
#define f first
#define s second

const int MAXN = 2e3 + 10;

// dp[i][j] stores maximum number of small cameras left given j large left and all up to i inclusive is taken
int dp[MAXN][MAXN];

int x[MAXN];

int N, P, Q;

set<pi> loc;

bool possible(int w) {
    for (int i = 0; i <= N; i++) {
        for (int j = 0; j <= Q; j++) {
            dp[i][j] = -1;
        }
    }

    dp[0][0] = P;

    for (pi cLoc : loc) {
        int i = cLoc.s;

        for (int nL = 0; nL <= Q; nL++) {
            // case 1: use large
            if (nL > 0) {
                int pI = prev(loc.lower_bound({x[i] - 2 * w + 1, -1}))->s;
                dp[i][nL] = max(dp[i][nL], dp[pI][nL - 1]);
            }

            //  case 2: use small
            int pI = prev(loc.lower_bound({x[i] - w + 1, -1}))->s;
            dp[i][nL] = max(dp[i][nL], dp[pI][nL] - 1);
        }
    }

    int lastI = prev(loc.end())->s;

    for (int nL = 0; nL <= Q; nL++) {
        if (dp[lastI][nL] >= 0) {
            return true;
        }
    }
    return false;
}


int binSearch() {
    int low = 1;
    int hi = 1e9;
    while (low != hi) {
        assert(low < hi);

        int mid = (low + hi) / 2;
        if (possible(mid)) {
            assert(hi != mid);

            hi = mid;
        } else {
            low = mid + 1;
        }
    }
    return low;
}

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

    cin >> N >> P >> Q;

    x[0] = -2e9;

    loc.insert({x[0], 0});

    for (int i = 1; i <= N; i++) {
        cin >> x[i];
        loc.insert({x[i], i});
    }

//    cout << possible(9) << endl;

    int ans = binSearch();
    cout << ans << endl;
}

Subtask #1
0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 768 KB Output is correct
2 Correct 5 ms 512 KB Output is correct
3 Correct 5 ms 384 KB Output is correct
4 Correct 6 ms 768 KB Output is correct
5 Execution timed out 1060 ms 1536 KB Time limit exceeded
6 Halted 0 ms 0 KB -

Subtask #2
0 / 50.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 8448 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Execution timed out 1100 ms 16256 KB Time limit exceeded
4 Halted 0 ms 0 KB -