main.go

// Source: https://leetcode.com/problems/count-prefix-and-suffix-pairs-i
// Title: Count Prefix and Suffix Pairs I
// Difficulty: Easy
// Author: Mu Yang <http://muyang.pro>

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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 <div aria-expanded="false" data-headlessui-state="" id="headlessui-popover-button-:ro:">prefix<div style="position: fixed; z-index: 40; inset: 0px auto auto 0px; transform: translate(480px, 257px);"> and a <div aria-expanded="false" data-headlessui-state="" id="headlessui-popover-button-:rq:">suffix<div style="position: fixed; z-index: 40; inset: 0px auto auto 0px; transform: translate(560px, 257px);"> 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.
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

import (
	"strings"
)

func countPrefixSuffixPairs(words []string) int {
	res := 0

	n := len(words)

	for i := 0; i < n; i++ {
		for j := i + 1; j < n; j++ {
			if strings.HasPrefix(words[j], words[i]) && strings.HasSuffix(words[j], words[i]) {
				res++
			}
		}
	}

	return res
}