Minimum Size Subarray Sum

Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead.

For example, given the array [2,3,1,2,4,3] and s = 7,
the subarray [4,3] has the minimal length under the problem constraint.

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More practice:

If you have figured out the O(n) solution, try coding another solution of which the time complexity is O(n log n).

public class Solution {
    public int minSubArrayLen(int s, int[] nums) {
        if (nums == null || nums.length == 0) {
            return 0;
        }
        int slow = 0;
        int fast = 0;
        int sum = 0;
        int res = Integer.MAX_VALUE;
        boolean find = false;
        while (fast < nums.length) {
            sum += nums[fast];
            fast++;
            while (sum >= s) {
                res = Math.min(res, fast - slow);
                find = true;
                sum -= nums[slow];
                slow++;
            }
        }
        if (find) {
            return res;
        } else {
            return 0;
        }
    }
}