Create 191-Number-of-1-Bits.java

java/191-Number-of-1-Bits.java

@@ -0,0 +1,28 @@
+//standard way
+public class Solution {
+    // you need to treat n as an unsigned value
+    public int hammingWeight(int n) {
+        int count = 0;
+        int mask = 1;
+        for (int i = 0; i < 32; i++) {
+            if ((n & mask) != 0) {
+                count++;
+            }
+            n >>= 1;
+        }
+        return count;
+    }
+}
+
+//smart way
+public class Solution {
+    // you need to treat n as an unsigned value
+    public int hammingWeight(int n) {
+        int count = 0;
+        while (n != 0) {
+            n = n & (n - 1);
+            count++;
+        }
+        return count;
+    }
+}