1413. Minimum Value to Get Positive Step by Step Sum

QUESTION:

Given an array of integers nums, you start with an initial positive value startValue.

In each iteration, you calculate the step by step sum of startValue plus elements in nums (from left to right).

Return the minimum positive value of startValue such that the step by step sum is never less than 1.

Example 1:

Input: nums = [-3,2,-3,4,2]
Output: 5
Explanation: If you choose startValue = 4, in the third iteration your step by step sum is less than 1.
step by step sum
startValue = 4 | startValue = 5 | nums
  (4 -3 ) = 1  | (5 -3 ) = 2    |  -3
  (1 +2 ) = 3  | (2 +2 ) = 4    |   2
  (3 -3 ) = 0  | (4 -3 ) = 1    |  -3
  (0 +4 ) = 4  | (1 +4 ) = 5    |   4
  (4 +2 ) = 6  | (5 +2 ) = 7    |   2

Example 2:

Input: nums = [1,2]
Output: 1
Explanation: Minimum start value should be positive.

Example 3:

Input: nums = [1,-2,-3]
Output: 5

Constraints:

1 <= nums.length <= 100
-100 <= nums[i] <= 100

EXPLANATION:

easy的题目, 简单的算术题. 设这个结果为x, 那么就是 x+foreach(sum) >= 1 那么只要算出 foreach(sum)的最小值, 然后加上1即可.

SOLUTION:

class Solution {
    func minStartValue(_ nums: [Int]) -> Int {
        var tmp:Int = 0
        var tmpSum:Int = 0
        for num in nums {
            tmpSum += num
            tmp = min(tmp,tmpSum)
        }
        return abs(tmp) + 1
    }
}
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