209. Minimum Size Subarray Sum

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LeetCode

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Problem

Given an array of positive integers nums and a positive integer target, return the minimal length of a subarray whose sum is greater than or equal to target. If there is no such subarray, return 0 instead.

Example 1:

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.

Example 2:

Input: target = 4, nums = [1,4,4]
Output: 1

Example 3:

Input: target = 11, nums = [1,1,1,1,1,1,1,1]
Output: 0

Constraints:

• $1 <= target <= 10^9$
• $1 <= nums.length <= 10^5$
• $1 <= nums[i] <= 10^4$

Code

862. Shortest Subarray with Sum at Least K

class Solution {
    public int minSubArrayLen(int target, int[] nums) {
        int res = Integer.MAX_VALUE;
        int left = 0;
        int sum = 0;

        for(int i = 0; i < nums.length; i++){
            sum += nums[i];
            while(left <= i && sum >= target){
                res = Math.min(res, i - left + 1);
                sum -= nums[left];
                left++;
            }
        }

        return res == Integer.MAX_VALUE ? 0 : res;
    }
}