main.cpp

// Source: https://leetcode.com/problems/minimum-absolute-difference
// Title: Minimum Absolute Difference
// Difficulty: Easy
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Given an array of **distinct** integers `arr`, find all pairs of elements with the minimum absolute difference of any two elements.
//
// Return a list of pairs in ascending order(with respect to pairs), each pair `[a, b]` follows
//
// - `a, b` are from `arr`
// - `a < b`
// - `b - a` equals to the minimum absolute difference of any two elements in `arr`
//
// **Example 1:**
//
// ```
// Input: arr = [4,2,1,3]
// Output: [[1,2],[2,3],[3,4]]
// Explanation: The minimum absolute difference is 1. List all pairs with difference equal to 1 in ascending order.```
//
// **Example 2:**
//
// ```
// Input: arr = [1,3,6,10,15]
// Output: [[1,3]]
// ```
//
// **Example 3:**
//
// ```
// Input: arr = [3,8,-10,23,19,-4,-14,27]
// Output: [[-14,-10],[19,23],[23,27]]
// ```
//
// **Constraints:**
//
// - `2 <= arr.length <= 10^5`
// - `-10^6 <= arr[i] <= 10^6`
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#include <climits>
#include <vector>

using namespace std;

// Sort
class Solution {
 public:
  vector<vector<int>> minimumAbsDifference(vector<int>& arr) {
    int n = arr.size();

    // Sort
    sort(arr.begin(), arr.end());

    // Find minimal difference
    auto minDiff = INT_MAX;
    for (auto i = 2; i < n; ++i) {
      minDiff = min(minDiff, arr[i] - arr[i - 1]);
    }

    // Count
    auto ans = vector<vector<int>>();
    for (auto i = 1; i < n; ++i) {
      if ((arr[i] - arr[i - 1]) == minDiff) {
        ans.push_back({arr[i - 1], arr[i]});
      }
    }

    return ans;
  }
};