1、尺取法，對于孤陋寡聞的我來說，刷題之前沒聽說過，后來了解了一下這個方法，感覺好多題目都可以用這個方法解決，在leetcode上有一類題叫做Two Pointers，其中一部分題目就應該使用尺取法來解決。

2、在介紹尺取法的使用之前，先看一個典型的實例Leetcode209. 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.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.