String - 28. Implement strStr()

#===================================
# Tanzila Islam
# Email: tanzilamohita@gmail.com
# Language: Python 3
#===================================

class Solution:
    def strStr(self, haystack: str, needle: str) -> int:
        h = len(haystack)
        n = len(needle)

        for i in range(h):
            if haystack[i:i+n]==needle:
                return i
        
        return -1