1144

1144. Decrease Elements To Make Array Zigzag (Medium)

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

Companies:
Google

Related Topics:
Array

Solution 1.

// OJ: https://leetcode.com/problems/decrease-elements-to-make-array-zigzag/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int movesToMakeZigzag(vector<int>& A) {
        int sum[2] = {}, N = A.size();
        for (int i = 0; i < N; ++i) sum[i % 2] += max(0, A[i] - min(i == 0 ? INT_MAX : A[i - 1], i == N - 1 ? INT_MAX : A[i + 1]) + 1);
        return min(sum[0], sum[1]);
    }
};