题解

#include <cstdio>
#include <algorithm>
using namespace std;
int n,m,t[505],mem[505][505];
int solve(int i,int st) {
    if (i == n + 1) return 0;
    if (st < t[i]) return solve(i, t[i]);
    if (mem[i][st - t[i]]) return mem[i][st - t[i]];
    int sum = 0,j = i;
    while (j <= n && t[j] <= st)
        sum += t[j++];
    int best = st * (j - i) - sum + solve(j, st + m);
    for (; j <= n; j++) {
        sum += t[j];
        best = min(t[j] * (j - i + 1) - sum + solve(j + 1, t[j] + m), best);
    }
    return mem[i][st - t[i]] = best;
}
int main() {
    scanf("%d%d",&n,&m);
    for (int i = 1; i <= n; i++)
        scanf("%d",&t[i]);
    sort(t + 1, t + n + 1);
    printf("%d\n",solve(1, 0));
    return 0;
}