Implement strStr()

Description:

For a given source string and a target string, you should output the first index(from 0) of target string in source string.
If target does not exist in source, just return -1.
Example
If source = “source” and target = “target”, return -1.
If source = “abcdabcdefg” and target = “bcd”, return 1.
Challenge
O(n2) is acceptable. Can you implement an O(n) algorithm (hint: KMP)

Code:

1.

class Solution:
 """
 @param: source: source string to be scanned.
 @param: target: target string containing the sequence of characters to match
 @return: a index to the first occurrence of target in source, or -1  if target is not part of source.
 """
 def strStr(self, source, target):
  # write your code here
  if target == "":
return 0
  if (target == None) or (source == None):
return -1
  return source.find(target) 

2.

class Solution:
 """
 @param: source: source string to be scanned.
 @param: target: target string containing the sequence of characters to match
 @return: a index to the first occurrence of target in source, or -1  if target is not part of source.
 """
 def strStr(self, source, target):
  # write your code here
  if target == "":
return 0
  if (target == None) or (source == None):
return -1
  ls = len(source)
  lt = len(target)
  for i in range(1+ls-lt):
if source[i] == target[0]:
 if source[i:lt+i] == target[:]:
  return i
  return -1