问题

### Instructions: You are an expert Python programmer. You will be given a question (problem specification) and will generate a correct Python program that matches the specification and passes all tests. You will NOT return anything except for the program.
### Question:
You are given a 0-indexed string array words.
Let's define a boolean function isPrefixAndSuffix that takes two strings, str1 and str2:

isPrefixAndSuffix(str1, str2) returns true if str1 is both a prefix and a suffix of str2, and false otherwise.

For example, isPrefixAndSuffix("aba", "ababa") is true because "aba" is a prefix of "ababa" and also a suffix, but isPrefixAndSuffix("abc", "abcd") is false.
Return an integer denoting the number of index pairs (i, j) such that i < j, and isPrefixAndSuffix(words[i], words[j]) is true.

Example 1:

Input: words = ["a","aba","ababa","aa"]
Output: 4
Explanation: In this example, the counted index pairs are:
i = 0 and j = 1 because isPrefixAndSuffix("a", "aba") is true.
i = 0 and j = 2 because isPrefixAndSuffix("a", "ababa") is true.
i = 0 and j = 3 because isPrefixAndSuffix("a", "aa") is true.
i = 1 and j = 2 because isPrefixAndSuffix("aba", "ababa") is true.
Therefore, the answer is 4.
Example 2:

Input: words = ["pa","papa","ma","mama"]
Output: 2
Explanation: In this example, the counted index pairs are:
i = 0 and j = 1 because isPrefixAndSuffix("pa", "papa") is true.
i = 2 and j = 3 because isPrefixAndSuffix("ma", "mama") is true.
Therefore, the answer is 2.
Example 3:

Input: words = ["abab","ab"]
Output: 0
Explanation: In this example, the only valid index pair is i = 0 and j = 1, and isPrefixAndSuffix("abab", "ab") is false.
Therefore, the answer is 0.

Constraints:

1 <= words.length <= 50
1 <= words[i].length <= 10
words[i] consists only of lowercase English letters.

### Format: You will use the following starter code to write the solution to the problem and enclose your code within delimiters.
```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:

```

### Answer: (use the provided format with backticks)

答案

模型 模型答案 正确答案
金声玉亮2.0 ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1, str2):
return str2.startswith(str1) and str2.endswith(str1)

count = 0
n = len(words)
for i in range(n):
for j in range(i + 1, n):
if isPrefixAndSuffix(words[i], words[j]):
count += 1

return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
deepseek-r1

```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
count = 0
n = len(words)
for i in range(n):
for j in range(i + 1, n):
s = words[i]
t = words[j]
if len(s) > len(t):
continue
if t.startswith(s) and t.endswith(s):
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
gpto1 ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1, str2):
if len(str1) > len(str2):
return False
return str2.startswith(str1) and str2.endswith(str1)

count = 0
n = len(words)
for i in range(n):
for j in range(i+1, n):
if isPrefixAndSuffix(words[i], words[j]):
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
gpt-4o-2024-08-06 ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1, str2):
return str2.startswith(str1) and str2.endswith(str1)

count = 0
n = len(words)

for i in range(n):
for j in range(i + 1, n):
if isPrefixAndSuffix(words[i], words[j]):
count += 1

return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
DeepSeek-Coder-V2-Lite-Instruct ```python
from typing import List

class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1, str2):
return str1 == str2[:len(str1)] and str1 == str2[-len(str1):]

count = 0
n = len(words)
for i in range(n):
for j in range(i + 1, n):
if isPrefixAndSuffix(words[i], words[j]):
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
Meta-Llama-3.1-405B-Instruct-Turbo ```python
from typing import List

class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
count = 0
for i in range(len(words)):
for j in range(i + 1, len(words)):
if words[i] == words[j][:len(words[i])] and words[i] == words[j][-len(words[i]):]:
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
Meta-Llama-3.1-70B-Instruct-Turbo ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
count = 0
for i in range(len(words)):
for j in range(i + 1, len(words)):
if words[i] == words[j][:len(words[i])] and words[i] == words[j][-len(words[i]):]:
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
Qwen2-72B-Instruct ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1, str2):
len1, len2 = len(str1), len(str2)
if len1 > len2:
return False
if str2[:len1] != str1 or str2[-len1:] != str1:
return False
return True

ans = 0
for i in range(len(words)):
for j in range(i + 1, len(words)):
if isPrefixAndSuffix(words[i], words[j]):
ans += 1
return ans
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
baichuan4 ```python
from typing import List

class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
count = 0
n = len(words)
for i in range(n):
for j in range(i+1, n):
if words[i] == words[j][-len(words[i]):] and words[i] == words[j][:len(words[i])]:
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
doubao ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
count = 0
for i in range(len(words)):
for j in range(i + 1, len(words)):
if words[i] == words[j][:len(words[i])] and words[i] == words[j][-len(words[i]):]:
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
gpto1 ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1, str2):
if len(str1) > len(str2):
return False
return str2.startswith(str1) and str2.endswith(str1)

count = 0
n = len(words)
for i in range(n):
for j in range(i+1, n):
if isPrefixAndSuffix(words[i], words[j]):
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
kimi ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1, str2):
return str1 == str2[:len(str1)] and str1 == str2[-len(str1):]

count = 0
for i in range(len(words)):
for j in range(i + 1, len(words)):
if isPrefixAndSuffix(words[i], words[j]):
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
minimax ```python
from typing import List

class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1: str, str2: str) -> bool:
return str2.startswith(str1) and str2.endswith(str1)

count = 0
for i in range(len(words)):
for j in range(i + 1, len(words)):
if isPrefixAndSuffix(words[i], words[j]):
count += 1
return count

# Example usage:
# sol = Solution()
# print(sol.countPrefixSuffixPairs(["a","aba","ababa","aa"])) # Output: 4
# print(sol.countPrefixSuffixPairs(["pa","papa","ma","mama"])) # Output: 2
# print(sol.countPrefixSuffixPairs(["abab","ab"])) # Output: 0
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
wenxinyiyan ```python
from typing import List

class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1: str, str2: str) -> bool:
return str2.startswith(str1) and str2.endswith(str1)

count = 0
n = len(words)
for i in range(n):
for j in range(i + 1, n):
if isPrefixAndSuffix(words[i], words[j]):
count += 1

return count
```
This solution defines a nested helper function `isPrefixAndSuffix` to check if a string `str1` is both a prefix and a suffix of another string `str2`. Then, it uses two nested loops to iterate over all possible index pairs `(i, j)` such that `i < j`. For each pair, it checks if `words[i]` is both a prefix and a suffix of `words[j]` using the helper function. If it is, the count is incremented. Finally, the count is returned as the result.		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
zhipu ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def isPrefixAndSuffix(str1, str2):
return str2.startswith(str1) and str2.endswith(str1)

count = 0
n = len(words)
for i in range(n):
for j in range(i + 1, n):
if isPrefixAndSuffix(words[i], words[j]):
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]
deepseek-v3 ```python
class Solution:
def countPrefixSuffixPairs(self, words: List[str]) -> int:
def is_prefix_and_suffix(str1, str2):
return str2.startswith(str1) and str2.endswith(str1)

count = 0
n = len(words)
for i in range(n):
for j in range(i+1, n):
if is_prefix_and_suffix(words[i], words[j]):
count += 1
return count
```		 [{"input": "[\"a\", \"aba\", \"ababa\", \"aa\"]", "output": "4", "testtype": "functional"}, {"input": "[\"pa\", \"papa\", \"ma\", \"mama\"]", "output": "2", "testtype": "functional"}, {"input": "[\"abab\", \"ab\"]", "output": "0", "testtype": "functional"}]