LeetCode [438] Find All Anagrams in a String

 438. Find All Anagrams in a String

Medium

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".

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class Solution { public List<Integer> findAnagrams(String s, String p) { List<Integer> list = new ArrayList<>(); int[] cp = new int[26]; int[] cs = new int[26]; int l = 0, r = 0, ns = s.length(), np = p.length(); for(char c : p.toCharArray()){ cp[c-'a']++; } while(r<ns){ int c = s.charAt(r++)-'a'; if(cp[c]==0){ l = r; cs = new int[26]; }else{ cs[c]++; while(cs[c]>cp[c]){ int c0 = s.charAt(l++)-'a'; cs[c0]--; } if(r-l==p.length()) list.add(l); } } return list; } }