438. Find All Anagrams in a String Easy

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Share 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".

思路：活动窗口

代码：python3

class Solution:
    def findAnagrams(self, s: str, p: str):
        #活动窗口
        m=len(s)
        n=len(p)
        #边界问题
        if m<n:return []
        shash=[0]*123
        phash=[0]*123
        res=[]
        # for x in s:
        #     shash[ord(x)]+=1
        for x in p:
        	phash[ord(x)]+=1
        #窗口
        for i in range(0,m):
            shash[ord(s[i])]+=1
            if i<n:
                pass
            else:
                shash[ord(s[i-n])]-=1
            if shash==phash:
                res.append(i-n+1)
        return res
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