# 6.07.2023 [209. Minimum Size Subarray Sum]

Min length subarray with `sum >= target`

6.07.2023

209. Minimum Size Subarray Sum medium
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Problem TLDR

Min length subarray with sum >= target

Intuition

Use two pointers: one adding to sum and another subtracting. As all numbers are positive, then sum will always be increasing with adding a number and deceasing when subtracting.

Approach

Let’s use Kotlin Sequence API

Complexity

• Time complexity:
  O(n)

• Space complexity:
  O(1)

Code

fun minSubArrayLen(target: Int, nums: IntArray): Int {
    var lo = 0
    var sum = 0
    return nums.asSequence().mapIndexed { hi, n ->
        sum += n
        while (sum - nums[lo] >= target) sum -= nums[lo++]
        (hi - lo + 1).takeIf { sum >= target }
    }
    .filterNotNull()
    .min() ?: 0
}