1144. Decrease Elements To Make Array Zigzag

Given an array nums of integers, a move consists of choosing any element and decreasing it by 1.

An array A is a zigzag array if either:

  • Every even-indexed element is greater than adjacent elements, ie. A[0] > A[1] < A[2] > A[3] < A[4] > ...
  • OR, every odd-indexed element is greater than adjacent elements, ie. A[0] < A[1] > A[2] < A[3] > A[4] < ...

Return the minimum number of moves to transform the given array nums into a zigzag array.

 

Example 1:

Input: nums = [1,2,3]
Output: 2
Explanation: We can decrease 2 to 0 or 3 to 1.

Example 2:

Input: nums = [9,6,1,6,2]
Output: 4

 

Constraints:

  • 1 <= nums.length <= 1000
  • 1 <= nums[i] <= 1000

Rust Solution

struct Solution;

impl Solution {
    fn moves_to_make_zigzag(nums: Vec<i32>) -> i32 {
        let mut sums = vec![0, 0];
        let n = nums.len();
        for i in 0..n {
            let mut adj = vec![];
            if i > 0 {
                adj.push(nums[i - 1]);
            }
            if i + 1 < n {
                adj.push(nums[i + 1]);
            }
            let min = adj.into_iter().min().unwrap();
            if nums[i] >= min {
                sums[i % 2] += (nums[i] - min) + 1;
            }
        }
        sums[0].min(sums[1])
    }
}

#[test]
fn test() {
    let nums = vec![1, 2, 3];
    let res = 2;
    assert_eq!(Solution::moves_to_make_zigzag(nums), res);
    let nums = vec![9, 6, 1, 6, 2];
    let res = 4;
    assert_eq!(Solution::moves_to_make_zigzag(nums), res);
    let nums = vec![10, 4, 4, 10, 10, 6, 2, 3];
    let res = 13;
    assert_eq!(Solution::moves_to_make_zigzag(nums), res);
}

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