Given an unsorted array, find out the most closest two elements in this array.

Solution:

• Sort is important here! You must think about sort first. Since other may may cost
• Then the gap between adjacent elements are the

public ArrayList<int[]> closestNumber(int[] arr){
    ArrayList<int[]> res = new ArrayList<>();
    if(arr == null || arr.length == 0)
        return res;
    Arrays.sort(arr);

    int mindiff = Integer.MAX_VALUE;
    for(int i = 1; i < arr.length; i++) {
         int curdiff = arr[i] - arr[i - 1];
         if(curdiff >= mindiff) {
             if(curdiff > mindiff)
                 res.clear();
             int[] cres = new int[]{arr[i - 1], arr[i]};
             res.add(cres);
         }
    }
    return res;
}