Quest_28_Implement_strStr

public class Solution
{
    public static void Main()
    {
        var haystack = "aaaaa";
        var needle = "bba";

        Solution solution = new Solution();
        var result = solution.StrStr(haystack, needle);
    }

    public int StrStr(string haystack, string needle)
    {
        if (string.IsNullOrEmpty(needle))
            return 0;

        int len = haystack.Length - needle.Length;
        for (int i = 0; i <= len; i++)
        {
            int j = i;
            foreach (var ch in needle)
            {
                if (ch != haystack[j])
                    break;
                j++;
            }

            if (j - i != needle.Length)
                continue;

            return i;
        }

        return -1;
    }
}