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Maximum difference between increasing elements

Tags : array, leetcode, cpp, easy

Problem Statement - link #

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.

Examples #

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 #

Solution #

class Solution {
public:
    int maximumDifference(vector<int>& nums) {
        int numsi = nums[0], diff = -1;
        for(int j=0 ; j < nums.size() ; j++){
            if(numsi < nums[j]){
                diff = max(diff,nums[j]-numsi);
            }else{
                numsi = min(nums[j],numsi);
            }
        }
        return diff;
    }
};