Array String Hash Map Sliding Window
Intermediate Level

Implement the minimumSizeSubarraySum method that returns the smallest subarray length whose sum reaches the target.

The input contains a positive integer array nums, its length size, and a target sum target. Your task is to find the minimum length of a continuous subarray whose sum is at least target.

If no such subarray exists, return 0.

For example, in [2,3,1,2,4,3] with target 7, the subarray [4,3] has length 2, so the answer is 2.

Example 1
Input:
nums (int[]) = [2,3,1,2,4,3]
size (int) = 6
target (int) = 7
Return:
(int) 2
Example 2
Input:
nums (int[]) = [1,4,4]
size (int) = 3
target (int) = 4
Return:
(int) 1
Example 3
Input:
nums (int[]) = [1,1,1,1]
size (int) = 4
target (int) = 5
Return:
(int) 0

Use a sliding window because the array contains positive numbers.

Expand the window by moving the right pointer and adding values to a running sum. When the sum becomes at least the target, try to shrink the window from the left to find a smaller valid length.

Keep the minimum valid length found. If no valid window is found, return 0.

Pseudocode:

function minimumSizeSubarraySum(nums, size, target):
    left = 0
    currentSum = 0
    best = infinity
    for right from 0 to size - 1:
        currentSum = currentSum + nums[right]
        while currentSum >= target:
            best = minimum(best, right - left + 1)
            currentSum = currentSum - nums[left]
            left++
    if best is infinity:
        return 0
    return best
Run your code to see the result.