init impl

Author: freemanzhang

src/string/TotalHammingDistance.java

@@ -0,0 +1,44 @@
+package string;
+
+/*
+The Hamming distance between two integers is the number of positions at which the corresponding bits are different.
+
+Now your job is to find the total Hamming distance between all pairs of the given numbers.
+
+Example:
+Input: 4, 14, 2
+
+Output: 6
+
+Explanation: In binary representation, the 4 is 0100, 14 is 1110, and 2 is 0010 (just
+showing the four bits relevant in this case). So the answer will be:
+HammingDistance(4, 14) + HammingDistance(4, 2) + HammingDistance(14, 2) = 2 + 2 + 2 = 6.
+Note:
+Elements of the given array are in the range of 0 to 10^9
+Length of the array will not exceed 10^4.
+ * */
+
+public class TotalHammingDistance
+{
+	public int totalHammingDistance( int[] nums )
+	{
+		int n = 31;
+		int len = nums.length;
+		int[] numOfOnes = new int[n];
+		
+		for ( int i = 0; i < len; i++ )
+		{
+			for ( int j = 0; j < n; j++ )
+			{
+				numOfOnes[j] += ( nums[i] >> j ) & 1;
+			}
+		}
+		
+		int sum = 0;
+		for ( int count : numOfOnes )
+		{
+			sum += count * ( len - count );
+		}
+		return sum;
+	}
+}