712. Minimum ASCII Delete Sum for Two Strings

Problem Link: https://leetcode.com/problems/minimum-ascii-delete-sum-for-two-strings/
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Complexity: Time-O(N^2), Memory-O(N^2), TimeTaken-<2hr
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Logic:
TBH you wont belive i spent >1.5hr just to find out a typo. 
We will use both i and j of strings as the dp state.
And will just add the ascii val with the next recurssion and return it.
If equal we will just return the recurssion. 

class Solution {
    int[][] dp;
    public int minimumDeleteSum(String s1, String s2) {
        dp=new int[s1.length()][s2.length()];
        for(int i=0;i<s1.length();i++)
            Arrays.fill(dp[i], -1);
        
        return traverse(s1.toCharArray(), 0, s2.toCharArray(), 0);
    }
    private int traverse(char[] ch1, int i, char[] ch2, int j){
        if(i==ch1.length && j==ch2.length)return 0;
        if(i==ch1.length)return toASCIISum(ch2, j);
        if(j==ch2.length)return toASCIISum(ch1, i);
        if(dp[i][j]!=-1)return dp[i][j];
        int val=0;
        int k1=ch1[i], k2=ch2[j];
        if(ch1[i]==ch2[j])
            val+=traverse(ch1, i+1, ch2, j+1);
        else
            val+=Math.min(traverse(ch1, i+1, ch2, j)+k1, traverse(ch1, i, ch2, j+1)+k2);
        dp[i][j]=val;
        return val;
    }
    private int toASCIISum(char[] ch, int i){
        int sum=0;
        for(int i1=i;i1<ch.length;i1++)
            sum+=ch[i1];
        return sum;
    }
}