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.


Test Cases

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:

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


Solution

class Solution {
public:
    int minSubArrayLen(int target, vector<int>& nums) {
        int start = 0, current = 0, end = 0, minlen = INT_MAX;
        while(end < nums.size()) {
            current += nums[end];
            while(current >= target) {
                minlen = min(minlen, end-start+1);
                current -= nums[start++];
            }
            end++;
        }
        return minlen == INT_MAX ? 0: minlen;
    }
};
class Solution {
    public int minSubArrayLen(int target, int[] nums) {
        int ml = Integer.MAX_VALUE;
        int start = 0, end = 0, curr = 0;
        while(end < nums.length) {
            curr += nums[end];
            while(curr >= target) {
                ml = Math.min(ml, end-start+1);
                curr -= nums[start++];
            }
            end++;
        }
        return ml == Integer.MAX_VALUE ? 0 : ml;
    }
}
Time Complexity: O(n)
Space Complexity: O(1)