Given an unsorted array, find the maximum difference between the successive elements in its sorted form.
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.
Given [1, 9, 2, 5], the sorted form of it is[1, 2, 5, 9], the maximum gap is between 5and 9 = 4.
Sort is easy but will cost O(nlogn) time. Try to solve it in linear time and space.
原文：http://www.cnblogs.com/grandyang/p/5838403.html