1、尺取法，对于孤陋寡闻的我来说，刷题之前没听说过，后来了解了一下这个方法，感觉好多题目都可以用这个方法解决，在leetcode上有一类题叫做Two Pointers，其中一部分题目就应该使用尺取法来解决。

2、在介绍尺取法的使用之前，先看一个典型的实例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.