Help leetcode problem?

1

this is a dp problem i have did this using recursion and memoization
but i am not able to think a iterative dp solution i mean top down approach
could any body help with explanation ?

code 
class Solution {
public:
    const int inf = 1e9 + 7;
    vector<vector<int>> dp;
    int solve(vector<int>&arr,int i,int k){
        if(i>=arr.size()){
            return k==0?0:inf;
        }
        else if(k<=0) return inf;
        else if(dp[i][k] != -1)
            return dp[i][k];
        
        int val = 0,ans = inf;
        for(int j=i; j<arr.size()-k+1; j++){
            val = max(val, arr[j]);
            ans = min(ans, val + solve(arr,j+1,k-1));
        }
        return dp[i][k] = ans;
    }
    int minDifficulty(vector<int>& arr, int d) {
        int n = arr.size();
        dp.assign(n+1,vector<int>(d+1,-1));
        int ans = solve(arr,0,d);
        return ans==inf?-1:ans;
    }
};