LeetCode 1413. Minimum Value to Get Positive Step by Step Sum

Description

https://leetcode.com/problems/minimum-value-to-get-positive-step-by-step-sum/

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

Starting from positive number 1 and check which minimum positive number can make the sum meets the requirement.

Python Solution

class Solution:
    def minStartValue(self, nums: List[int]) -> int:        
        start_value  = 1
        
        is_found = False
        
        while not is_found:
            
            summing = start_value
            
            i = 0
            while i < len(nums):
                summing += nums[i]
                
                if summing < 1:
                    break
                
                i += 1
                
            if i == len(nums):
                is_found = True
            else:
                start_value += 1
        
        return start_value
  • Time Complexity: O(N).
  • Space Complexity: O(1).

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