solves #2164: Sort Even and Odd Indices Independently in java

Author: anishLearnsToCode

Diff for: README.md

@@ -710,8 +710,8 @@
 | 2144 | [Minimum Cost of Buying Candies With Discount](https://leetcode.com/problems/minimum-cost-of-buying-candies-with-discount)                                             |                                                                           [![Java](assets/java.png)](src/MinimumCostOfBuyingCandiesWithDiscount.java)                                                                            |                                                                                                                                   |
 | 2148 | [Count Elements With Strictly Smaller and Greater Elements](https://leetcode.com/problems/count-elements-with-strictly-smaller-and-greater-elements)                   |                                                                     [![Java](assets/java.png)](src/CountElementsWithStrictlySmallerAndGreaterElements.java)                                                                      |                                                                                                                                   |
 | 2154 | [Keep Multiplying Found Values by Two](https://leetcode.com/problems/keep-multiplying-found-values-by-two)                                                             |                                                                               [![Java](assets/java.png)](src/KeepMultiplyingFoundValuesByTwo.java)                                                                               |                                                                                                                                   |
-| 2160 | [Minimum Sum of Four Digit Number After Splitting Digits](https://leetcode.com/problems/minimum-sum-of-four-digit-number-after-splitting-digits)                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
-| 2164 | [Sort Even and Odd Indices Independently](https://leetcode.com/problems/sort-even-and-odd-indices-independently)                                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 2160 | [Minimum Sum of Four Digit Number After Splitting Digits](https://leetcode.com/problems/minimum-sum-of-four-digit-number-after-splitting-digits)                       |                                                                       [![Java](assets/java.png)](src/MinimumSumOfFourDigitNumberAfterSplittingDigits.java)                                                                       |                                                                                                                                   |
+| 2164 | [Sort Even and Odd Indices Independently](https://leetcode.com/problems/sort-even-and-odd-indices-independently)                                                       |                                                                             [![Java](assets/java.png)](src/SortEvenAndOddIndicesIndependently.java)                                                                              |                                                                                                                                   |
 | 2169 | [Count Operations to Obtain Zero](https://leetcode.com/problems/count-operations-to-obtain-zero)                                                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2176 | [Count Equal and Divisible Pairs in an Array](https://leetcode.com/problems/count-equal-and-divisible-pairs-in-an-array)                                               |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2180 | [Count Integers With Even Digit Sum](https://leetcode.com/problems/count-integers-with-even-digit-sum)                                                                 |                                                                                [![Java](assets/java.png)](src/CountIntegersWithEvenDigitSum.java)                                                                                |                                                                                                                                   |

Diff for: src/MinimumSumOfFourDigitNumberAfterSplittingDigits.java

@@ -0,0 +1,23 @@
+// https://leetcode.com/problems/minimum-sum-of-four-digit-number-after-splitting-digits
+// T: O(1)
+// S: O(1)
+
+import java.util.Arrays;
+
+public class MinimumSumOfFourDigitNumberAfterSplittingDigits {
+    public int minimumSum(int num) {
+        final int digit1 = num / 1000;
+        final int digit2 = (num / 100) % 10;
+        final int digit3 = (num / 10) % 10;
+        final int digit4 = num % 10;
+
+        final int[] digits = { digit1, digit2, digit3, digit4 };
+        Arrays.sort(digits);
+
+        return toNumber(digits[0], digits[2]) + toNumber(digits[1], digits[3]);
+    }
+
+    private int toNumber(int a, int b) {
+        return 10 * a + b;
+    }
+}

Diff for: src/SortEvenAndOddIndicesIndependently.java

@@ -0,0 +1,28 @@
+// https://leetcode.com/problems/sort-even-and-odd-indices-independently
+// T: O(n log(n))
+// S: O(n)
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+public class SortEvenAndOddIndicesIndependently {
+    public int[] sortEvenOdd(int[] nums) {
+        final int[] even = new int[(nums.length + 1) / 2];
+        final Integer[] odd = new Integer[nums.length / 2];
+
+        for (int i = 0 ; i < nums.length ; i++) {
+            if (i % 2 == 0) even[i / 2] = nums[i];
+            else odd[i / 2] = nums[i];
+        }
+
+        Arrays.sort(even);
+        Arrays.sort(odd, Comparator.reverseOrder());
+
+        for (int i = 0 ; i < nums.length ; i++) {
+            if (i % 2 == 0) nums[i] = even[i / 2];
+            else nums[i] = odd[i / 2];
+        }
+
+        return nums;
+    }
+}