Submission #236828

#	Time	Username	Problem	Language	Result	Execution time	Memory
236828		apostoldaniel854	Watching (JOI13_watching)	C++14	100 / 100	276 ms	16120 KiB

watching

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
#define pb push_back
#define dbg(x) cerr << #x << " " << x << "\n"



void _ (int &a, int b) {
    if (a > b)
        a = b;
}
const int N = 2000;
int dp[1 + N][1 + N];
int a[1 + N];
int n, p, q;

bool check (int w) {
    for (int i = 0; i <= n; i++)
        for (int j = 0; j <= p; j++)
            dp[i][j] = q + 1;
    dp[0][0] = 0;
    int x = 0, y = 0;
    for (int i = 1; i <= n; i++) {
        while (a[x] + w <= a[i])
            x++;
        if (x)
            x--;
        while (a[y] + 2 * w <= a[i])
            y++;
        if (y)
            y--;
        for (int j = 0; j <= p; j++) {
            if (j)
                _ (dp[i][j], dp[x][j - 1]);
            _ (dp[i][j], dp[y][j] + 1);
        }
    }
    for (int i = 0; i <= p; i++)
        if (dp[n][i] <= q)
            return true;
    return false;
}

int main () {
    cin >> n >> p >> q;
    _ (p, n);
    _ (q, n);
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    sort (a + 1, a + n + 1);
    int lb = 1, rb = (1 << 30);
    int bestW = 0;
    while (lb <= rb) {
        int mid = (lb + rb) / 2;
        if (check (mid))
            bestW = mid, rb = mid - 1;
        else
            lb = mid + 1;
    }
    cout << bestW << "\n";
    return 0;
}

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