lec10_17.cpp

class Solution {
    public: 
        int f(int i ,int  j){
            if(i == 0 && j == 0) return 1;
            if(i<0 || j<0) return 0 ;
    
            int up = f(i-1, j);
            int left = f(i , j-1);
    
            return up+left;
        }
        int uniquePaths(int m, int n) {
            return f(m-1, n-1);
        }
    };