LC#338 returns array containting bit counts, O(NlogN) time, O(N) Space

Author: NirmalSilwal

Leetcode/easy/CountingBits338.java

@@ -0,0 +1,40 @@
+package easy;
+
+import java.util.Arrays;
+
+public class CountingBits338 {
+
+public static int[] countBits(int n) {
+int[] ans = new int[n + 1];
+
+for (int i = 0; i <= n; i++) {
+ans[i] = countBinaryOnes(i);
+}
+return ans;
+}
+
+private static int countBinaryOnes(int num) {
+int count = 0;
+int mask = 1;
+
+while (num != 0) {
+if ((num & mask) != 0)
+count++;
+
+num = num >> 1; // right shift
+}
+return count;
+}
+
+public static void main(String[] args) {
+System.out.println(Arrays.toString(countBits(2)));
+System.out.println(Arrays.toString(countBits(5)));
+System.out.println(Arrays.toString(countBits(0)));
+}
+}
+
+/* output:
+[0, 1, 1]
+[0, 1, 1, 2, 1, 2]
+[0]
+*/