[LEEDCode][028][简单] – 实现strStr()（implement-strstr）

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

实现 strStr() 函数。

给定一个 haystack 字符串和一个 needle 字符串，在 haystack 字符串中找出 needle 字符串出现的第一个位置 (从0开始)。如果不存在，则返回 -1。

示例 1:

<strong>输入:</strong> haystack = "hello", needle = "ll"
<strong>输出:</strong> 2

1 2	<strong>输入:</strong> haystack = "hello", needle = "ll" <strong>输出:</strong> 2

示例 2:

<strong>输入:</strong> haystack = "aaaaa", needle = "bba"
<strong>输出:</strong> -1

1 2	<strong>输入:</strong> haystack = "aaaaa", needle = "bba" <strong>输出:</strong> -1

说明:

当 needle 是空字符串时，我们应当返回什么值呢？这是一个在面试中很好的问题。

对于本题而言，当 needle 是空字符串时我们应当返回 0 。这与C语言的 strstr() 以及 Java的 indexOf() 定义相符。

解答

class Solution:
    def strStr(self, haystack, needle):
        """
        :type haystack: str
        :type needle: str
        :rtype: int
        """
        return haystack.find(needle)

class Solution:

def strStr(self, haystack, needle):

"""

:type haystack: str

:type needle: str

:rtype: int

"""

return haystack.find(needle)

自测用例

try:
    haystack = "hello"
    needle = "ll"
    result_1 = 2
    result_2 = Solution().strStr(haystack, needle)
    print('{} - {}'.format(result_1, result_2))
except Exception as e:
    print(e)

try:
    haystack = "aaaaa"
    needle = "bba"
    result_1 = -1
    result_2 = Solution().strStr(haystack, needle)
    print('{} - {}'.format(result_1, result_2))
except Exception as e:
    print(e)

try:
    haystack = "aaaaa"
    needle = ""
    result_1 = 0
    result_2 = Solution().strStr(haystack, needle)
    print('{} - {}'.format(result_1, result_2))
except Exception as e:
    print(e)

try:

haystack = "hello"

needle = "ll"

result_1 = 2

result_2 = Solution().strStr(haystack, needle)

print('{} - {}'.format(result_1, result_2))

except Exception as e:

print(e)

try:

haystack = "aaaaa"

needle = "bba"

result_1 = -1

result_2 = Solution().strStr(haystack, needle)

print('{} - {}'.format(result_1, result_2))

except Exception as e:

print(e)

try:

haystack = "aaaaa"

needle = ""

result_1 = 0

result_2 = Solution().strStr(haystack, needle)

print('{} - {}'.format(result_1, result_2))

except Exception as e:

print(e)

执行结果

提交时间	状态	执行用时	语言
几秒前	通过	44 ms	python3

解答

自测用例

执行结果

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