LeetCode 2310. The number of digits is the sum of integers of K

LeetCode 2310. The number of digits is K The sum of the integers of

Multiple backpack DP

const int N = 3010;
class Solution {
    
public:
    int f[N][N], v[N]; // front i No more than j The minimum number of 
    int minimumNumbers(int num, int k) {
    
        int n  = 0;
        for(int i = k; i <= num; i += 10)
                n ++,v[n] = i;

        memset(f, 0x3f, sizeof f);
        f[0][0] = 0;
        for(int i = 1; i <= n; i ++)
            for(int j = 0; j <= num; j ++)
            {
    
                f[i][j] = f[i - 1][j];
                if(j >= v[i])
                    f[i][j] = min(f[i][j], f[i][j - v[i]] + 1); // Note that f[i][j - v[i]] + 1
            }

        if(f[n][num] == 0x3f3f3f3f) 
            f[n][num] = -1;

        return f[n][num];
    }
};