Maximum Gap

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.

hint:

　　Bucket Sort

public class MaxGap {
    public int maximumGap(int[] nums) {
        if (nums == null || nums.length < 2)
            return 0;
        int max = Integer.MIN_VALUE, min = Integer.MAX_VALUE;
        for (int i = 0; i < nums.length; i++) {
            if (max < nums[i]) max = nums[i];
            if (min > nums[i]) min = nums[i];
        }
        int bucket = (max - min) / nums.length + 1; // the bucket size is at least 1
        int n = (max - min) / bucket + 1;
        int[] mins = new int[n];
        int[] maxs = new int[n];
        for (int i = 0; i < n; i++) {
            mins[i] = Integer.MAX_VALUE;
            maxs[i] = Integer.MIN_VALUE;
        }
        for (int i = 0; i < nums.length; i++) {
            int k = (nums[i] - min) / bucket;
            if (mins[k] > nums[i]) mins[k] = nums[i];
            if (maxs[k] < nums[i]) maxs[k] = nums[i];
        }
        int maxGap = 0, pre = 0;
        for (int i = 1; i < n; i++) {
            if (mins[i] <= max) {
                if (maxGap < mins[i] - maxs[pre]) {
                    maxGap = mins[i] - maxs[pre];
                }
                pre = i;
            }
        }
        return maxGap;
    }
    public static void main(String[] args) {
        int[] nums = {1, 1000};
        MaxGap mg = new MaxGap();
        System.out.println(mg.maximumGap(nums));
    }
}