store it in arr to avoid further repetitive work in future function calls
arr [ m - 1 ] [ n - 1 ] [ o - 1 ] = 1 + lcs ( X , Y , Z , m - 1 , n - 1 , o - 1 ) NEW_LINE return arr [ m - 1 ] [ n - 1 ] [ o - 1 ] NEW_LINE else : NEW_LINE