Leetcode 209 - Minimum size subarray sum

Given an array of positive integers nums and a positive integer target, return the minimal length of a contiguous subarray [numsl, numsl+1, …, numsr-1, numsr] of which the sum is greater than or equal to target. If there is no such subarray, return 0 instead.

Note: For questions like finding a subarray that fits some requirements, sliding window is usually the way to go.

Example 1:

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Input: target = 7, nums = [2,3,1,2,4,3]
Output: 2
Explanation: The subarray [4,3] has the minimal length under the problem constraint.
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/**
* @param {number} target
* @param {number[]} nums
* @return {number}
*/
var minSubArrayLen = function(target, nums) {
let left = 0, right = 0;
let sum = 0, length = Infinity;
while (right < nums.length) {
sum += nums[right];
if (sum < target) {
right++;
} else {
while (sum >= target) {
length = Math.min(length, right - left + 1);
sum -= nums[left];
left++;
}
right++;
}
}
return length === Infinity ? 0 : length;
};