209. Minimum Size Subarray Sum
Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous subarray of which the sum ≥ s. If there isn't one, return 0 instead.
**Example: **
Input: s = 7, nums = [2,3,1,2,4,3] Output: 2 Explanation: the subarray [4,3] has the minimal length under the problem constraint.
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).
思路：
使用sliding window来做，一个指针遍历数组，一个指针记录起始位置。
代码：
java：
代码语言：javascript复制class Solution {
public int minSubArrayLen(int s, int[] nums) {
int from = 0, sum = 0, win = Integer.MAX_VALUE;
for (int i = 0; i < nums.length; i ) {
sum = nums[i];
while (from <= i && sum >= s) {
win = Math.min(win, i - from 1);
sum -= nums[from ];
}
}
return win == Integer.MAX_VALUE ? 0 : win;
}
}
