438. Find All Anagrams in a String（不太懂）

题目

Given a string
s and a non-empty string p, find all the start indices ofp's anagrams in
s.
Strings consists of lowercase English letters only and the length of both stringss 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".

答案解法（还不是很理解）

public class Solution {

public List<Integer> findAnagrams(String s, String p) {

List<Integer> list = new ArrayList<>();
if (s == null || s.length() == 0 || p == null || p.length() == 0) return list;
int[] hash = new int[256];
for (char c : p.toCharArray())
hash[c]++;
int left = 0, right = 0, count = p.length();
while (right < s.length()) {
if (hash[s.charAt(right)] >= 1)
count--;
hash[s.charAt(right)]--;
right++;
if (count == 0)
list.add(left);
if (right - left == p.length() ) {
if (hash[s.charAt(left)] >= 0)
count++;
hash[s.charAt(left)]++;
left++;
}
}
return list;
}
}

点击打开链接，