LeetCode - Maximum Gap

Maximum Gap

2015.1.23 15:00

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.

Solution:

　　This here is not an O(n) solution, but O(n * log(n)). Sort the array and find the maximal gap.

　　As for a linear solution, I'm searching for it...

　　Discussions online said it could be solved using bucket sort, but that doesn't really satisfy O(n) time scale, right? At least I wouldn't take it for O(n).

Accepted code:

 1 // 1AC, not an O(n) solution, though, one not yet come up with...

 2 #include <algorithm>

 3 using namespace std;

 4 

 5 class Solution {

 6 public:

 7     int maximumGap(vector<int> &num) {

 8         sort(num.begin(), num.end());

 9         int n;

10         

11         n = (int)num.size();

12         if (n < 2) {

13             return 0;

14         }

15         

16         int i;

17         int ans = abs(num[0] - num[1]);

18         for (i = 2; i < n; ++i) {

19             ans = max(ans, abs(num[i - 1] - num[i]));

20         }

21         

22         return ans;

23     }

24 private:

25     int max(const int &x, const int &y) {

26         return x > y ? x : y;

27     }

28     

29     int abs(const int &x) {

30         return x >= 0 ? x : -x;

31     }

32 };