fix number_of_1_bits

Author: 0xmountaintop

kamyu104/src/main.rs

@@ -1,5 +1,5 @@
+mod number_of_1_bits;
 mod reverse_bits;
 mod single_number;
 mod single_number_ii;
-mod number_of_1_bits;
 mod template;

kamyu104/src/number_of_1_bits.rs

@@ -1,8 +1,16 @@
+// Time:  O(logn) = O(32)
+// Space: O(1)
+
 pub struct Solution {}
 
 impl Solution {
-    pub fn hamming_weight(n: i32) -> i32 {
-        n
+    pub fn hamming_weight(mut n: u32) -> u8 {
+        let mut cnt: u8 = 0;
+        while n > 0 {
+            cnt += 1;
+            n &= n - 1;
+        }
+        return cnt;
     }
 }
 
@@ -12,7 +20,23 @@ mod tests {
 
     #[test]
     fn test_hamming_weight() {
-        assert_eq!(Solution::hamming_weight(3), 3);
-        assert_eq!(Solution::hamming_weight(4), 4);
+        assert_eq!(
+            Solution::hamming_weight(
+                u32::from_str_radix("00000000000000000000000000001011", 2).unwrap()
+            ),
+            3
+        );
+        assert_eq!(
+            Solution::hamming_weight(
+                u32::from_str_radix("00000000000000000000000010000000", 2).unwrap()
+            ),
+            1
+        );
+        assert_eq!(
+            Solution::hamming_weight(
+                u32::from_str_radix("11111111111111111111111111111101", 2).unwrap()
+            ),
+            31
+        );
     }
 }