191. Number of 1 Bits Easy

1/**
2 * [191] Number of 1 Bits
3 *
4 * Write a function that takes an unsigned integer and returns the number of '1' bits it has (also known as the <a href="http://en.wikipedia.org/wiki/Hamming_weight" target="_blank">Hamming weight</a>).
5 * Note:
6 * 
7 * 	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.
8 * 	In Java, the compiler represents the signed integers using <a href="https://en.wikipedia.org/wiki/Two%27s_complement" target="_blank">2's complement notation</a>. Therefore, in Example 3, the input represents the signed integer. -3.
9 * 
10 *  
11 * Example 1:
12 * 
13 * Input: n = 00000000000000000000000000001011
14 * Output: 3
15 * Explanation: The input binary string 00000000000000000000000000001011 has a total of three '1' bits.
16 * 
17 * Example 2:
18 * 
19 * Input: n = 00000000000000000000000010000000
20 * Output: 1
21 * Explanation: The input binary string 00000000000000000000000010000000 has a total of one '1' bit.
22 * 
23 * Example 3:
24 * 
25 * Input: n = 11111111111111111111111111111101
26 * Output: 31
27 * Explanation: The input binary string 11111111111111111111111111111101 has a total of thirty one '1' bits.
28 * 
29 *  
30 * Constraints:
31 * 
32 * 	The input must be a binary string of length 32.
33 * 
34 *  
35 * Follow up: If this function is called many times, how would you optimize it?
36 */
37pub struct Solution {}
38
39// problem: https://leetcode.com/problems/number-of-1-bits/
40// discuss: https://leetcode.com/problems/number-of-1-bits/discuss/?currentPage=1&orderBy=most_votes&query=
41
42// submission codes start here
43
44impl Solution {
45    pub fn hammingWeight (n: u32) -> i32 {
46        0
47    }
48}
49
50// submission codes end
51
52#[cfg(test)]
53mod tests {
54    use super::*;
55
56    #[test]
57    fn test_191() {
58    }
59}
60