✡ leetcode 164. Maximum Gap 寻找最大相邻数字差 --------- java

Given an unsorted array, find the maximum difference between the successive elements in its sorted form.

Try to solve it in linear time/space.

Return 0 if the array contains less than 2 elements.

You may assume all elements in the array are non-negative integers and fit in the 32-bit signed integer range.

给定一个未排序的数组，然后找出排序之后的数组中，相邻数字的最大差。

1、桶排序

public class Solution {
    public int maximumGap(int[] nums) {
        int len = nums.length;
        if (len < 2){
            return 0;
        }
        int max = nums[0];
        int min = nums[0];
        for (int num : nums){
            if (max < num){
                max = num;
            } else if ( min > num){
                min = num;
            }
        }
        int gap = (max-min)/(len-1);
        if( gap == 0){
            gap = 1;
        }
        int size = (max - min) / gap + 1;
        int[] gapMax = new int[size];
        int[] gapMin = new int[size];
        for (int num : nums){
            int pos = (num - min)/gap;
            if (gapMax[pos] < num){
                gapMax[pos] = num;
            } 
            if (gapMin[pos] == 0 || gapMin[pos] > num){
                gapMin[pos] = num;
            }
        }
        int start = min;
        int end = gapMax[0];
        int result = end - start;
        for (int i = 0; i < size - 1; i++){
            start = gapMax[i] == 0 ? start : gapMax[i];
            end = gapMin[i+1];
            if (result < (end - start)){
                result = end - start;
            }
        }
        if (gapMax[size - 1] == 0 && end - start > result){
            result = end - start;
        } else if (gapMax[size - 1] != 0 && end - gapMax[size - 1] > result){
            result = end - gapMax[size - 1];
        }
        return result;
    }
}