solves sort integers by number of 1 bits

Author: anishLearnsToCode

README.md

@@ -346,7 +346,7 @@
 | 1342 | [Number of Steps to Reduce a Number to Zero](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-to-zero)                               |                                                       [![Java](assets/java.png)](src/NumberOfStepsToReduceANumberToZero.java)                                                        |                                                                                                                                   |
 | 1346 | [Check if N and It's Double Exist](https://leetcode.com/problems/check-if-n-and-its-double-exist)                                                    |                       [![Java](assets/java.png)](src/CheckIfNAndItsDoubleExist.java) [![Python](assets/python.png)](python/check_if_n_and_its_double_exist.py)                       |                                                                                                                                   |
 | 1351 | [Count Negative Numbers In A Sorted Matrix](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix)                                 |                                                       [![Java](assets/java.png)](src/CountNegativeNumbersInSortedMatrix.java)                                                        |                                                                                                                                   |
-| 1356 | [Sort Integers by Number of 1 Bits](https://leetcode.com/problems/sort-integers-by-the-number-of-1-bits)                                             |                                                                                                                                                                                      |                                                                                                                                   |
+| 1356 | [Sort Integers by Number of 1 Bits](https://leetcode.com/problems/sort-integers-by-the-number-of-1-bits)                                             |                                                         [![Java](assets/java.png)](src/SortIntegersByTheNumberOf1Bits.java)                                                          |                                                                                                                                   |
 | 1360 | [Number of Days Between Two Dates](https://leetcode.com/problems/number-of-days-between-two-dates)                                                   |                                                                                                                                                                                      |                                                                                                                                   |
 | 1365 | [How Many Numbers Are Smaller Than Current Number](https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number)               |                                                                                                                                                                                      |                                                                                                                                   |
 | 1370 | [Increasing Decreasing String](https://leetcode.com/problems/increasing-decreasing-string)                                                           |                                                                                                                                                                                      |                                                                                                                                   |

src/SortIntegersByTheNumberOf1Bits.java

@@ -0,0 +1,31 @@
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class SortIntegersByTheNumberOf1Bits {
+    public int[] sortByBits(int[] array) {
+        List<Integer> sorted = Arrays.stream(array).boxed().sorted((a, b) -> {
+            final int setBits1 = setBits(a), setBits2 = setBits(b);
+            if (setBits1 == setBits2) return Integer.compare(a, b);
+            return Integer.compare(setBits1, setBits2);
+        }).collect(Collectors.toList());
+        return toArray(sorted);
+    }
+
+    private int[] toArray(List<Integer> array) {
+        final int[] result = new int[array.size()];
+        for (int index = 0 ; index < result.length ; index++) {
+            result[index] = array.get(index);
+        }
+        return result;
+    }
+
+    private int setBits(int number) {
+        int setBits = 0;
+        while (number > 0) {
+            setBits += number & 1;
+            number >>= 1;
+        }
+        return setBits;
+    }
+}