1827. 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

Example 3:

Input: nums = [8]
Output: 0

 

Constraints:

  • 1 <= nums.length <= 5000
  • 1 <= nums[i] <= 104

Rust Solution

struct Solution;

impl Solution {
    fn min_operations(mut nums: Vec<i32>) -> i32 {
        let n = nums.len();
        let mut res = 0;
        for i in 1..n {
            let target = nums[i - 1] + 1;
            if nums[i] < target {
                res += target - nums[i];
                nums[i] = target;
            }
        }
        res
    }
}

#[test]
fn test() {
    let nums = vec![1, 1, 1];
    let res = 3;
    assert_eq!(Solution::min_operations(nums), res);
    let nums = vec![1, 5, 2, 4, 1];
    let res = 14;
    assert_eq!(Solution::min_operations(nums), res);
    let nums = vec![8];
    let res = 0;
    assert_eq!(Solution::min_operations(nums), res);
}

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