排序邻数差值

public static int (int[] arr){
    if(arr == null || arr.length == 0){
        return 0;
    }
    int len = arr.length;
    int max = Integer.MIN_VALUE;
    int min = Integer.MAX_VALUE;
    for(int i = 0; i  <len; i++){
        max = Math.max(arr[i], max);
        min = Math.min(arr[i], min);
    }
    if(max == min){
        return 0;
    }
    int[] maxArr = new int[len+1];
    int[] minArr = new int[len+1];
    boolean[] hasNum = new boolean[len + 1];
    int k = 0;
    for(int i = 0; i < len; i++){
        k = getBucket(arr[i], max, min, len);
        maxArr[k] = hasNum[k] ? Math.max(arr[i], maxArr[k]) : arr[i];
        minArr[k] = hasNum[k] ? Math.min(arr[i], minArr[k]) : arr[i];
        hasNum[k] = true;
    }
    int lastMax = 0;
    int nextMin = 0;
    int i = 0;
    for(; i<len; i++){
        if(!hasNum[i]){
            lastMax = maxArr[i-1];
            break;
        }
    }
    while(i<len+1){
        if(hasNum[i]){
            nextMin = minArr[i];
            break;
        }
        i++;
    }
    return nextMin - lastMax;
}

 * 计算进入哪个桶  max直接放入n+1桶中 
 */
public static int getBucket(int num, int max, int min, int len){
    return ((num - min) * len) / (max - min);
}