都不难的，每个都是原题。正常准备的话，大概十几分钟能够完成。我们csoahelp完成这次的OA大概花了20分钟左右。

**1. 4th Bit**

A binary number is a combination of 1s and 0s. Its *n[**t**h*] least significant digit is the *n[**t**h*] digit starting from the right starting with 1. Given a decimal number, convert it to binary and determine the value of the 4th least significant digit.

**Example**

number = 23

- Convert the decimal number 23 to binary number: 2310=24+23+21+20=(10111)22310=24+23+21+20=(10111)2.
- The value of the 4th index from the right in the binary representation is 0.

**Function Description**

Complete the function `fourthBit`

in the editor below.

`fourthBit`

has the following parameter(s):

`int number`

: a decimal integer

**Returns**:

`int`

: an integer 0 or 1 matching the 4th least significant digit in the binary representation of`number`

.

**Constraints**

- 0≤
*n**u**mb**er*<2^31

**2. Break a Palindrome**

A palindrome reads the same from left or right, *mom* for example. There is a palindrome which must be modified, if possible. Change exactly one character of the string to another character in the range ascii[a-z] so that the string meets the following three conditions:

- The new string is lower alphabetically than the initial string.
- The new string is the lowest value string alphabetically that can be created from the original palindrome after making only one change.
- The new string is not a palindrome.

Return the new string, or, if it not possible to create a string meeting the criteria, return the string *IMPOSSIBLE*.

**Example**

`palindromeStr = 'aaabbbaaa'`

- Possible strings lower alphabetically than
`aaabbbaaa`

after one change are [`aaaabaaaa`

]. `aaaabaaaa`

is not a palindrome and is the lowest string that can be created from`palindromeStr`

.

**Function Description**

Complete the function `breakPalindrome`

in the editor below.

`breakPalindrome`

has the following parameter(s):

`string palindromeStr`

: the original string

**3. Which of the following operators has the lowest precedence?**

- Ternary operator (?:)
- Comma operator (,)
- Sizeof operator (sizeof)
- Member access operator (.)

**4. Are you an expert on data structures?**

Which of the following data structures can erase from its beginning or its end in O(1) time?

- vector
- deque
- stack
- segment tree

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