{ "data": { "question": { "questionId": "3309", "questionFrontendId": "3042", "categoryTitle": "Algorithms", "boundTopicId": 2644029, "title": "Count Prefix and Suffix Pairs I", "titleSlug": "count-prefix-and-suffix-pairs-i", "content": "
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
.
\n
Example 1:
\n\n\nInput: words = ["a","aba","ababa","aa"]\nOutput: 4\nExplanation: In this example, the counted index pairs are:\ni = 0 and j = 1 because isPrefixAndSuffix("a", "aba") is true.\ni = 0 and j = 2 because isPrefixAndSuffix("a", "ababa") is true.\ni = 0 and j = 3 because isPrefixAndSuffix("a", "aa") is true.\ni = 1 and j = 2 because isPrefixAndSuffix("aba", "ababa") is true.\nTherefore, the answer is 4.\n\n
Example 2:
\n\n\nInput: words = ["pa","papa","ma","mama"]\nOutput: 2\nExplanation: In this example, the counted index pairs are:\ni = 0 and j = 1 because isPrefixAndSuffix("pa", "papa") is true.\ni = 2 and j = 3 because isPrefixAndSuffix("ma", "mama") is true.\nTherefore, the answer is 2.\n\n
Example 3:
\n\n\nInput: words = ["abab","ab"]\nOutput: 0\nExplanation: In this example, the only valid index pair is i = 0 and j = 1, and isPrefixAndSuffix("abab", "ab") is false.\nTherefore, the answer is 0.\n\n
\n
Constraints:
\n\n1 <= words.length <= 50
1 <= words[i].length <= 10
words[i]
consists only of lowercase English letters.给你一个下标从 0 开始的字符串数组 words
。
定义一个 布尔 函数 isPrefixAndSuffix
,它接受两个字符串参数 str1
和 str2
:
str1
同时是 str2
的前缀(prefix)和后缀(suffix)时,isPrefixAndSuffix(str1, str2)
返回 true
,否则返回 false
。例如,isPrefixAndSuffix(\"aba\", \"ababa\")
返回 true
,因为 \"aba\"
既是 \"ababa\"
的前缀,也是 \"ababa\"
的后缀,但是 isPrefixAndSuffix(\"abc\", \"abcd\")
返回 false
。
以整数形式,返回满足 i < j
且 isPrefixAndSuffix(words[i], words[j])
为 true
的下标对 (i, j)
的 数量 。
\n\n
示例 1:
\n\n\n输入:words = [\"a\",\"aba\",\"ababa\",\"aa\"]\n输出:4\n解释:在本示例中,计数的下标对包括:\ni = 0 且 j = 1 ,因为 isPrefixAndSuffix(\"a\", \"aba\") 为 true 。\ni = 0 且 j = 2 ,因为 isPrefixAndSuffix(\"a\", \"ababa\") 为 true 。\ni = 0 且 j = 3 ,因为 isPrefixAndSuffix(\"a\", \"aa\") 为 true 。\ni = 1 且 j = 2 ,因为 isPrefixAndSuffix(\"aba\", \"ababa\") 为 true 。\n因此,答案是 4 。\n\n
示例 2:
\n\n\n输入:words = [\"pa\",\"papa\",\"ma\",\"mama\"]\n输出:2\n解释:在本示例中,计数的下标对包括:\ni = 0 且 j = 1 ,因为 isPrefixAndSuffix(\"pa\", \"papa\") 为 true 。\ni = 2 且 j = 3 ,因为 isPrefixAndSuffix(\"ma\", \"mama\") 为 true 。\n因此,答案是 2 。\n\n
示例 3:
\n\n\n输入:words = [\"abab\",\"ab\"]\n输出:0\n解释:在本示例中,唯一有效的下标对是 i = 0 且 j = 1 ,但是 isPrefixAndSuffix(\"abab\", \"ab\") 为 false 。\n因此,答案是 0 。\n\n
\n\n
提示:
\n\n1 <= words.length <= 50
1 <= words[i].length <= 10
words[i]
仅由小写英文字母组成。(i, j)
, such that i < j
, and check isPrefixAndSuffix(words[i], words[j])
.",
"The answer is the total number of pairs where isPrefixAndSuffix(words[i], words[j]) == true
."
],
"solution": null,
"status": null,
"sampleTestCase": "[\"a\",\"aba\",\"ababa\",\"aa\"]",
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