Leetcode: 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.

click to show more practice.

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).

 1 public class Solution {
 2     public int minSubArrayLen(int s, int[] nums) {
 3         int minWin = Integer.MAX_VALUE;
 4         int l=0, r=0;
 5         if (nums==null || nums.length==0) return 0;
 6         int sum = 0;
 7         while (r < nums.length) {
 8             sum += nums[r];
 9             while (sum >= s) {
10                 minWin = Math.min(minWin, r-l+1);
11                 sum -= nums[l++];
12             }
13             r++;
14         }
15         if (r==nums.length && l==0 && sum<s) return 0;
16         return minWin;
17     }
18 }

 1 public class Solution {
 2     public int minSubArrayLen(int s, int[] nums) {
 3         int minWin = Integer.MAX_VALUE;
 4         int l=0, r=0;
 5         if (nums==null || nums.length==0) return 0;
 6         int sum = 0;
 7         while (r < nums.length) {
 8             sum += nums[r];
 9             if (sum >= s) { //found one feasible window, try to shrink the window
10                 while (l<=r && sum-nums[l] >= s) {
11                     sum -= nums[l++];
12                 }
13                 minWin = Math.min(minWin, r-l+1);
14             }
15             r++;
16         }
17         if (r==nums.length && l==0 && sum<s) return 0;
18         return minWin;
19     }
20 }