Pascal's Triangle

Input: numRows = 5
Output: [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]

 //each  nth row has n numbers

// first and last no is always 1

                         1

                    1          1

              1           2           1

         1         3          3            1

 vector<vector<int>> generate(int numRows) {
        vector<vector<int>> r(numRows);
        
        for (int i = 0; i < numRows; i++) {
            r[i].resize(i + 1);
            r[i][0] = r[i][i] = 1;
 
            for (int j = 1; j < i; j++)
                r[i][j] = r[i - 1][j - 1] + r[i - 1][j];
        }
        
        return r;
    }

 

 

 if we need to find the value at r row and c col :

formula is 

              r-1 

                     C

                          c-1 

if we are given to print a particular row:

nCr  ->    n= row  , r=col 

 

 

for(int =0;i<k;i++)

{

res*=(n-i);

res/=(i+1);

}