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.

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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] <= 10^5

Solution

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class Solution {
    public int minSubArrayLen(int target, int[] nums) {
        int start = 0;
        int end = 0;
        int n = nums.length;
        int sum = 0;
        int minLen = Integer.MAX_VALUE;
        while (end < n) {
            
            sum += nums[end];
            
            end++;
            
            
            while (sum >= target) {
                minLen = Math.min(minLen, end - start);
                sum -= nums[start];
                start++;
            }
            
        }
        
        return minLen == Integer.MAX_VALUE ? 0: minLen;
    }
}

Solution#

Solution