solves find subsequence of length k with the largest sum

Author: anishLearnsToCode

README.md

@@ -497,5 +497,5 @@
 | 2085 | [Count Common Words With One Occurrence](https://leetcode.com/problems/count-common-words-with-one-occurrence)                                            |                                                        [![Java](assets/java.png)](src/CountCommonWordsWithOneOccurrence.java)                                                        |                                                                                                                                   |
 | 2089 | [Find Target Indices After Sorting Array](https://leetcode.com/problems/find-target-indices-after-sorting-array)                                          |                                                       [![Java](assets/java.png)](src/FindTargetIndicesAfterSortingArray.java)                                                        |                                                                                                                                   |
 | 2094 | [Finding 3-Digit Even Numbers](https://leetcode.com/problems/finding-3-digit-even-numbers)                                                                |                                                            [![Java](assets/java.png)](src/Finding3DigitEvenNumbers.java)                                                             |                                                                                                                                   |
-| 2099 | [Find Subsequence of Length K With the Largest Sum](https://leetcode.com/problems/find-subsequence-of-length-k-with-the-largest-sum)                      |                                                                                                                                                                                      |                                                                                                                                   |
+| 2099 | [Find Subsequence of Length K With the Largest Sum](https://leetcode.com/problems/find-subsequence-of-length-k-with-the-largest-sum)                      |                                                    [![Java](assets/java.png)](src/FindSubsequenceOfLengthKWithTheLargestSum.java)                                                    |                                                                                                                                   |
 | 2103 | [Rings and Rods](https://leetcode.com/problems/rings-and-rods)                                                                                            |                                                                                                                                                                                      |                                                                                                                                   |

src/FindSubsequenceOfLengthKWithTheLargestSum.java

@@ -0,0 +1,51 @@
+// https://leetcode.com/problems/find-subsequence-of-length-k-with-the-largest-sum
+// T: O(nloogn + klogk)
+// S: o(n)
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+public class FindSubsequenceOfLengthKWithTheLargestSum {
+    public int[] maxSubsequence(int[] nums, int k) {
+        List<Number>numbers = toNumbersList(nums);
+        numbers.sort(Comparator.comparingInt(a -> a.value));
+        List<Number> topK = getLastK(numbers, k);
+        topK.sort(Comparator.comparing(a -> a.index));
+        return toArray(topK);
+    }
+
+    private List<Number> toNumbersList(int[] array) {
+        final List<Number> numbers = new ArrayList<>(array.length);
+        for (int index = 0 ; index < array.length ; index++) {
+            numbers.add(new Number(array[index], index));
+        }
+        return numbers;
+    }
+
+    private List<Number> getLastK(List<Number> numbers, int k) {
+        final List<Number> result = new ArrayList<>();
+        for (int i = 0 ; i < k ; i++) {
+            result.add(numbers.get(numbers.size() - 1 - i));
+        }
+        return result;
+    }
+
+    private int[] toArray(List<Number> numbers) {
+        final int[] array = new int[numbers.size()];
+        for (int i = 0 ; i < array.length ; i++) {
+            array[i] = numbers.get(i).value;
+        }
+        return array;
+    }
+
+    private static final class Number {
+        private final int value;
+        private final int index;
+
+        private Number(int value, int index) {
+            this.value = value;
+            this.index = index;
+        }
+    }
+}