Implement strStr()

Question

Implement strStr().

Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Tags

• String
• Two Pointers

Thought

Use the brute force search algorithm.

Code

class Solution(object):
    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """
        if len(haystack) < len(needle):
            return -1
        if needle == '':
            return 0
        for i in xrange(len(haystack) - len(needle) + 1):
            if haystack[i] != needle[0]:
                continue
            j = 0
            while j < len(needle):
                if haystack[i + j] != needle[j]:
                    break
                j += 1
            if j == len(needle):
                return i
        return -1