[LeetCode] 438. Find All Anagrams in a String

轉自LeetCode

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".

<Solution>

這題是 242. Valid Anagram 的進階題

解題想法如下

• 一樣使用 hash map 來當作查表

• 利用兩個指標，來做一個 window 的概念，歷遍 s

• 當 p 裡面的字元都用光的時候，檢查是否符合條件，並且更新狀態

這類的題目有一個樣版，可參考這篇文章

code 如下

Java