lec10_19.cpp

class Solution {
    public: 
        int f(int i ,int  j,vector<vector<int>>&dp){
            if(i == 0 && j == 0) return 1;
            if(i<0 || j<0) return 0 ;
            if( dp[i][j]!= -1) return dp[i][j];
            int up = f(i-1, j, dp);
            int left = f(i , j-1,dp);
    
            return dp[i][j] = up+left;
        }
        int uniquePaths(int m, int n) {
            int dp[m][n] ;
    
            for(int i = 0 ; i<m; i++)
            {
                for(int j = 0 ; j<n; j++)
                {
                    if(i == 0 && j == 0 ) dp[i][j] = 1;
                    else{
                        int up = 0 ;
                        int left = 0 ;
                        if(i>0) up = dp[i-1][j];
                        if(j>0 ) left = dp[i][j-1];
                        dp[i][j] = up + left;
                    }
                }
                
            }
    
            return dp[m-1][n-1];
        }
    };