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+https://leetcode.com/problems/find-all-anagrams-in-a-string/discuss/92059/O(n)-Sliding-Window-JAVA-Solution-Extremely-Detailed-Explanation
+
+#  题目
+Given two strings s and p, return an array of all the start indices of p's anagrams in s. You may return the answer in any order.
+
+An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.
+
+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".
+```
+Constraints:
+
+- 1 <= s.length, p.length <= 3 * 104
+- s and p consist of lowercase English letters.
+
+q2a