14 Days Study Plan to Crack Algo I
231. Power of Two
Given an integer
true if it is a power of two. Otherwise, return
n is a power of two, if there exists an integer
x such that
n == 2x.
Input: n = 1
Explanation: 20 = 1
Input: n = 16
Explanation: 24 = 16
Input: n = 3
-231 <= n <= 231 - 1
Follow up: Could you solve it without loops/recursion?
Write a function that takes an unsigned integer and returns the number of ‘1’ bits it has (also known as the Hamming weight).
- Note that in some languages, such as Java, there is no unsigned integer type. In this case, the input will be given as a signed integer type. It should not affect your implementation, as the integer’s internal binary representation is the same, whether it is signed or unsigned.
- In Java, the compiler represents the signed integers using 2’s complement notation. Therefore, in Example 3, the input represents the signed integer.
Input: n = 00000000000000000000000000001011
Explanation: The input binary string 00000000000000000000000000001011 has a total of three '1' bits.
Input: n = 00000000000000000000000010000000
Explanation: The input binary string 00000000000000000000000010000000 has a total of one '1' bit.
Input: n = 11111111111111111111111111111101
Explanation: The input binary string 11111111111111111111111111111101 has a total of thirty one '1' bits.
- The input must be a binary string of length
Follow up: If this function is called many times, how would you optimize it?