algorithm/leetcode-master
1
0
Fork 0
mirror of https://github.com/youngyangyang04/leetcode-master.git synced 2025-07-07 15:45:40 +08:00
Code Issues Packages Projects Releases Wiki Activity

Update 0028.实现strStr.md

Browse Source
This commit is contained in:
jianghongcheng
2023-05-06 19:47:55 -05:00
committed by GitHub
parent 3cf5502868
commit 1fbd900c6a
1 changed files with 46 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files

133
problems/0028.实现strStr.md
View File

@ -692,107 +692,66 @@ class Solution {
```
Python3：
（版本一）前缀表（不减一）
（版本一）前缀表（减一）
```python
class Solution:
def getNext(self, next, s):
j = -1
next[0] = j
for i in range(1, len(s)):
while j >= 0 and s[i] != s[j+1]:
j = next[j]
if s[i] == s[j+1]:
j += 1
next[i] = j
def strStr(self, haystack: str, needle: str) -> int:
if not needle:
return 0
next = [0] * len(needle)
self.getNext(next, needle)
j = -1
for i in range(len(haystack)):
while j >= 0 and haystack[i] != needle[j+1]:
j = next[j]
if haystack[i] == needle[j+1]:
j += 1
if j == len(needle) - 1:
return i - len(needle) + 1
return -1
```
（版本二）前缀表（不减一）
```python
class Solution:
def getNext(self, next: List[int], s: str) -> None:
j = 0
next[0] = 0
for i in range(1, len(s)):
while j > 0 and s[i] != s[j]:
j = next[j - 1]
if s[i] == s[j]:
j += 1
next[i] = j
def strStr(self, haystack: str, needle: str) -> int:
if len(needle) == 0:
return 0
next = self.getNext(needle)
next = [0] * len(needle)
self.getNext(next, needle)
j = 0
for i in range(len(haystack)):
while j >= 1 and haystack[i] != needle[j]:
j = next[j-1]
while j > 0 and haystack[i] != needle[j]:
j = next[j - 1]
if haystack[i] == needle[j]:
j += 1
if j == len(needle):
return i - len(needle) + 1
return -1
def getNext(self, needle):
next = [0] * len(needle)
j = 0
next[0] = j
for i in range(1, len(needle)):
while j >= 1 and needle[i] != needle[j]:
j = next[j-1]
if needle[i] == needle[j]:
j += 1
next[i] = j
return next
```
（版本二）前缀表（减一）
```python
class Solution:
def strStr(self, haystack: str, needle: str) -> int:
a = len(needle)
b = len(haystack)
if a == 0:
return 0
next = self.getnext(a,needle)
p=-1
for j in range(b):
while p >= 0 and needle[p+1] != haystack[j]:
p = next[p]
if needle[p+1] == haystack[j]:
p += 1
if p == a-1:
return j-a+1
return -1
def getnext(self,a,needle):
next = ['' for i in range(a)]
k = -1
next[0] = k
for i in range(1, len(needle)):
while (k > -1 and needle[k+1] != needle[i]):
k = next[k]
if needle[k+1] == needle[i]:
k += 1
next[i] = k
return next
```
（版本三）前缀表（减一）
```python
class Solution:
def strStr(self, haystack: str, needle: str) -> int:
a = len(needle)
b = len(haystack)
if a == 0:
return 0
i = j = 0
next = self.getnext(a, needle)
while(i < b and j < a):
if j == -1 or needle[j] == haystack[i]:
i += 1
j += 1
else:
j = next[j]
if j == a:
return i-j
else:
return -1
def getnext(self, a, needle):
next = ['' for i in range(a)]
j, k = 0, -1
next[0] = k
while(j < a-1):
if k == -1 or needle[k] == needle[j]:
k += 1
j += 1
next[j] = k
else:
k = next[k]
return next
```
（版本四）暴力法
（版本三）暴力法
```python
class Solution(object):
def strStr(self, haystack, needle):
@ -807,7 +766,7 @@ class Solution(object):
return i
return -1
```
（版本五）使用 index
（版本四）使用 index
```python
class Solution:
def strStr(self, haystack: str, needle: str) -> int:
@ -816,7 +775,7 @@ class Solution:
except ValueError:
return -1
```
（版本六）使用 find
（版本五）使用 find
```python
class Solution:
def strStr(self, haystack: str, needle: str) -> int: