Leetcode
Two Pointers
String
题目¶
[Easy]
Implement strStr().
Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Example 1:
Input: haystack = "hello", needle = "ll" Output: 2
Example 2:
Input: haystack = "aaaaa", needle = "bba" Output: -1
中文题目¶
实现字符串子串匹配函数strStr()。如果字符串A是字符串B的子串，则返回A在B中首次出现的地址，否则返回-1。
实际应用中常用KMP算法，但是比较复杂。
思路¶
brute-force: 一一比对
def strStr(self, haystack, needle): if needle == "": return 0 for i in range(len(haystack)-len(needle)+1): for j in range(len(needle)): if haystack[i+j] != needle[j]: break if j == len(needle)-1: return i return -1
也可借用python直接对比
class Solution(object): def strStr(self, haystack, needle): """ :type haystack: str :type needle: str :rtype: int """ for i in range(len(haystack) - len(needle)+1): if haystack[i:i+len(needle)] == needle: return i return -1
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