"""

Implement strStr().

Returns the index of the first occurrence of needle in haystack, or -1 if

needle is not part of haystack.

"""

class Solution(object):

def strStr(self, haystack, needle):

"""

:type haystack: str

:type needle: str

:rtype: int

needle: | n |

haystack: | n - m | m |

"""

n = len(haystack)

m = len(needle)

for i in range(n + 1 - m):

for k in range(m):

if haystack[i + k] != needle[k]:

break

else:

return i

return -1