closes holds the closing price of a stock on consecutive days. Return a list of the day-to-day changes: element i of the answer is closes[i + 1] - closes[i]. The result has one fewer element than the input (and is empty when there are fewer than two days).
Examples
Input: closes = [10, 12, 9, 9]
Output: [2, -3, 0]
Input: closes = [5]
Output: []
Constraints
0 <= len(closes) <= 10**5- Target: O(n) time.
Goals
- Produce a list one element shorter than the input
- Index neighbouring pairs safely