leetcode 438[easy]---Find All Anagrams in a String
Given a string s and a non-empty string p, find all the start indices of p's anagrams in s.
Strings consists of lowercase English letters only and the length of both strings s and p will not be larger than 20,100.
The order of output does not matter.
Example 1:
Input: s: "cbaebabacd" p: "abc" Output: [0, 6] Explanation: The substring with start index = 0 is "cba", which is an anagram of "abc". The substring with start index = 6 is "bac", which is an anagram of "abc".
Example 2:
Input: s: "abab" p: "ab" Output: [0, 1, 2] Explanation: The substring with start index = 0 is "ab", which is an anagram of "ab". The substring with start index = 1 is "ba", which is an anagram of "ab". The substring with start index = 2 is "ab", which is an anagram of "ab".
Seen this question in a real interview before? No
思路：给出一个较长的string S 和一个较短的string P，看p的顺序打乱后的所有可能的字符串在s中能不能找到，找得到就把所有找到的开始的位置记录下来。。
学习一种思维模式，先构建两个dict，将相同长度的S和P（P的长度）分别导入两个dict中，value对应字母出现的次数。（想了很久才想清楚原code为什么要有这几步，因为S 和P的长度不一样，用这几步奠定dict的长度，并在以后的步骤中保持住，为比较S和P提供基础保证。）
用while循环比较，（“if sdic==pdic”是否在dict中，只要key：value相同，就代表两个dict相同，不用考虑key出现的顺序），删除掉已经出现过的字母，保证两个dic的key的数量相同。