LeetCode-in-Java

2016. Maximum Difference Between Increasing Elements

Easy

Given a 0-indexed integer array nums of size n, find the maximum difference between nums[i] and nums[j] (i.e., nums[j] - nums[i]), such that 0 <= i < j < n and nums[i] < nums[j].

Return the maximum difference. If no such i and j exists, return -1.

Example 1:

Input: nums = [7,1,5,4]

Output: 4

Explanation:

The maximum difference occurs with i = 1 and j = 2, nums[j] - nums[i] = 5 - 1 = 4.

Note that with i = 1 and j = 0, the difference nums[j] - nums[i] = 7 - 1 = 6, but i > j, so it is not valid.

Example 2:

Input: nums = [9,4,3,2]

Output: -1

Explanation:

There is no i and j such that i < j and nums[i] < nums[j].

Example 3:

Input: nums = [1,5,2,10]

Output: 9

Explanation:

The maximum difference occurs with i = 0 and j = 3, nums[j] - nums[i] = 10 - 1 = 9.

Constraints:

• n == nums.length
• 2 <= n <= 1000
• 1 <= nums[i] <= 109

Solution

public class Solution {
    public int maximumDifference(int[] nums) {
        int mini = nums[0];
        int ans = -1;
        for (int i = 0; i < nums.length - 1; i++) {
            if (nums[i] < mini) {
                mini = nums[i];
            }
            if (nums[i + 1] - mini > ans) {
                ans = nums[i + 1] - mini;
            }
        }
        return ans <= 0 ? -1 : ans;
    }
}

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