98: 模拟赛-神光 dp

 

$code$

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int n, p, q, a[2001], l = 1, r = 0, ans = 0;
int dp[2001][2001], P[2001], Q[2001];

bool check(int L) {
    memset(dp, 0, sizeof(dp));
    memset(P, 0, sizeof(P));
    memset(Q, 0, sizeof(Q));
    for (int i = 1; i <= n; i++)
        for (int j = i; j <= n; j++) {
            if (a[j] - a[i] + 1<= L) P[i] = j;
            if (a[j] - a[i] + 1<= 2*L) Q[i] = j;
        }
    P[n+1] = Q[n+1] = n;
    for (int i = 0; i <= p; i++)
        for (int j = 0; j <= q; j++) {
            if (i > 0) dp[i][j] = max(dp[i][j], P[dp[i-1][j] + 1]);
            if (j > 0) dp[i][j] = max(dp[i][j], Q[dp[i][j-1] + 1]);
        }
    return dp[p][q] == n;
}

int main() {
    scanf("%d%d%d", &n, &p, &q);
    for (int i = 1; i <= n; i++)
        scanf("%d", &a[i]);
    sort(a + 1, a + 1 + n);
    a[0] = 0;
    r = a[n] - a[1] + 1;
    if (p + q >= n) {
        printf("1
");
        return 0;
    }
    while (l <= r) {
        int mid = (l+r) / 2;
        if (check(mid)) ans = mid, r = mid -1;
        else l = mid + 1;
    }
    printf("%d
", ans);
    return 0;
}