Dynamic Prograaming-438. Find All Anagrams in a String

public class Solution {
    public IList<int> FindAnagrams(string s, string p) {

        if(s.Length < p.Length){
            return new List<int>();
        }

        var maps1 = new Dictionary<char,int>();

        for(int i=0; i<p.Length;i++)
        {
            if(maps1.ContainsKey(p[i]))
            {
                maps1[p[i]]= maps1[p[i]]+1;
            }
            else {maps1[p[i]]=1;}
        }

        var res = new List<int>();

        for(int i=0; i<p.Length;i++)
        {
            if(maps1.ContainsKey(s[i]))
            {
                maps1[s[i]]--;
            }
            else {maps1[s[i]]=-1;}
        }

        var all_zero = 1;
        foreach(var n in maps1.Values)
        {
            if(n!=0){
                all_zero = 0;
            }
        }
        if(all_zero == 1){
            res.Add(0);
        }


        int k = p.Length;
        for(int i=k; i<s.Length;i++)
        {
            if(maps1.ContainsKey(s[i]))
            {
                maps1[s[i]]--;
            }
            else {maps1[s[i]]=-1;}

            if(maps1.ContainsKey(s[i-k]))
            {
                maps1[s[i-k]] = maps1[s[i-k]]+1;
            }
            else maps1[s[i-k]] = 1;

            all_zero = 1;
            foreach(var n in maps1.Values)
            {
                if(n!=0){
                    all_zero = 0;
                }
            }
            if(all_zero == 1){
                res.Add(i-k+1);
            }
        }

        return res;

    }
}