The first approach involves sorting the array and then iterating through it to find the pairs with the minimum absolute difference. By sorting, the smallest differences can only occur between consecutive elements. Hence, we sort the array and compute differences between adjacent elements to find the minimum difference.
Steps:
Time Complexity: O(n log n), due to sorting the array. Space Complexity: O(1), not considering the output space.
1import java.util.ArrayList;
2import java.util.Arrays;
3import java.util.List;
4
5class Solution {
6 public List<List<Integer>> minimumAbsDifference(int[] arr) {
7 Arrays.sort(arr);
8 int minDiff = Integer.MAX_VALUE;
9 List<List<Integer>> result = new ArrayList<>();
10 for (int i = 1; i < arr.length; i++) {
11 int diff = arr[i] - arr[i - 1];
12 if (diff < minDiff) {
13 minDiff = diff;
14 result.clear();
15 result.add(Arrays.asList(arr[i - 1], arr[i]));
16 } else if (diff == minDiff) {
17 result.add(Arrays.asList(arr[i - 1], arr[i]));
18 }
19 }
20 return result;
21 }
22}
23The Java solution sorts the array and finds the minimum absolute difference between consecutive elements, updating the result list according to whether a new minimum is found or if the minimum difference is maintained.
The second approach compares all pairs of elements to determine their absolute differences. This method ensures that all possible pairs are considered, and the pairs with the minimum difference are identified. Although not as efficient as the first approach, it explicitly checks every possible pair.
Steps:
Time Complexity: O(n^2), considering all pair combinations. Space Complexity: O(1), excluding result space.
1import java.util.ArrayList;
2import java.util.List;
3
4class Solution {
5 public List<List<Integer>> minimumAbsDifference(int[] arr) {
6 int minDiff = Integer.MAX_VALUE;
7 List<List<Integer>> result = new ArrayList<>();
8 for (int i = 0; i < arr.length; i++) {
9 for (int j = i + 1; j < arr.length; j++) {
10 int diff = Math.abs(arr[i] - arr[j]);
11 if (diff < minDiff) {
12 minDiff = diff;
13 result.clear();
14 result.add(List.of(arr[i], arr[j]));
15 } else if (diff == minDiff) {
16 result.add(List.of(arr[i], arr[j]));
17 }
18 }
19 }
20 return result;
21 }
22}
23The Java approach explicitly investigates each element pair, calculating their differences, updating the minimum difference, and storing viable pairs in a list that is returned on completion.