Minimum Operations to Make the Array Increasing

You are given an integer array nums (0-indexed). In one operation, you can choose an element of the array and increment it by 1.

• For example, if nums = [1,2,3], you can choose to increment nums[1] to make nums = [1,3,3].

Return the minimum number of operations needed to make nums strictly increasing.

An array nums is strictly increasing if nums[i] < nums[i+1] for all 0 <= i < nums.length - 1. An array of length 1 is trivially strictly increasing.

Example 1:

Input: nums = [1,1,1]
Output: 3
Explanation: You can do the following operations:
1) Increment nums[2], so nums becomes [1,1,2].
2) Increment nums[1], so nums becomes [1,2,2].
3) Increment nums[2], so nums becomes [1,2,3].

Example 2:

Input: nums = [1,5,2,4,1]
Output: 14

Approach

C++

#include <bits/stdc++.h>
using namespace std;

int minOperations(vector<int> &nums)
{

    int count = 0;
    int max1 = nums[0];

    for (int i = 1; i < nums.size(); i++)
    {
        if (nums[i] > max1)
        {
            max1 = nums[i];
        }
        else
        {
            int prev = nums[i];
            nums[i] = max1 + 1;
            count += nums[i] - prev;
            max1 = nums[i];
        }
    }
    return count;
}

int main()
{
    vector<int> nums = {1, 1, 1};

    cout << minOperations(nums) << "\n";

    return 0;
}