Find all anagrams of a string in another string?

public List<int> FindAnagrams(string s, string p) {
List<int> result = new List<int>();
if (p.Length > s.Length) return result;
int[] pCount = new int[26];
int[] sCount = new int[26];

Follow on:

for (int i = 0; i < p.Length; i++) {

pCount[p[i] - 'a']++;

sCount[s[i] - 'a']++;

}
if (Enumerable.SequenceEqual(pCount, sCount))

result.Add(0);

for (int i = p.Length; i < s.Length; i++) {

sCount[s[i] - 'a']++;

sCount[s[i - p.Length] - 'a']--;

if (Enumerable.SequenceEqual(pCount, sCount))

result.Add(i - p.Length + 1);

}
return result;
}

Explanation:

Sliding window with frequency count arrays for the pattern and current window.