appending takes 1 step , and we directly reach index i * 2 + 1 after appending so the number of steps is stord in i * 2 + 1
if ( s1 == s2 ) : NEW_LINE INDENT dp [ i * 2 + 1 ] = min ( dp [ i ] + 1 , dp [ i * 2 + 1 ] ) NEW_LINE DEDENT return dp [ n - 1 ] NEW_LINE