days lists a trader's daily result: positive numbers are gains, negative numbers are losses. Return the smallest possible total of a non-empty contiguous run of days, i.e. the worst streak.
Examples
Input: days = [3, -4, 2, -5, 1]
Output: -7
Explanation: Days 2 to 4 total -4 + 2 - 5 = -7.
Input: days = [1, 2, 3]
Output: 1
Explanation: Every run is positive; the single day worth 1 is the smallest.
Constraints
1 <= len(days) <= 10**5,-10**4 <= days[i] <= 10**4.- Target complexity: O(n) time, O(1) extra space.
Goals
- Adapt the running-best subarray idea to minimisation
- Decide at every step whether to extend the current run or restart it