29. Print shortest common Supersequence

29 Print shortest common Supersequence
Video Link : https://youtu.be/VDhRg-ZJTuc
Leetcode problem Link : https://leetcode.com/problems/shortest-common-supersequence/

                  ------->>>>>>>>>>>------------>>>>>>>>>>>>________CODE________<<<<<<<<<<<<------------<<<<<<<<<<<<<<<<<<<<<<<<<<<
                  
  string shortestCommonSupersequence(string s1, string s2) {
        
         int n=s1.size(); 
        int m=s2.size();
        int t[n+1][m+1]; 
        
        string res; 
        
        // compute LCS length using top-down approach 
        
    for(int i=0;i<=n;i++)
    {
        for(int j=0;j<=m;j++)
        {
            if(i==0||j==0)
                t[i][j]=0;
            else if(s1[i-1]==s2[j-1])
            {
                t[i][j]=1+t[i-1][j-1];
            }
            else
            {
                t[i][j]=max(t[i-1][j],t[i][j-1]);
            }
        }
    }  
        
       // to print lcs
        
        
    int i=n,j=m;
    while(i>0 && j>0)
    {
        if(s1[i-1]==s2[j-1])
        {
            res.push_back(s1[i-1]);
            i--;
            j--;
        }
        else
        {
            if(t[i-1][j]>t[i][j-1])
            {
                res.push_back(s1[i-1]);
                i--;
            } else{
                res.push_back(s2[j-1]);
                j--;
            }
        }
    }
     
        // we need to fill the remaining characters when either of i or  j becomes zero 
        
    while(i>0) // if s1 characters are still left
    {
        res.push_back(s1[i-1]);
        i--;
    }
    while(j>0) //if s2 characters are still left
    {
        res.push_back(s2[j-1]);
        j--;
        
    }
        reverse(res.begin(),res.end()); 
        return res;
    }