[golang] 151. Reverse Words in a String

// [url]https://leetcode.com/studyplan/top-interview-150/[/url]
 
package topInterview
 
import (
    "strings"
)
 
// reverseWords
//
// 151. Reverse Words in a String
//
// Given an input string s, reverse the order of the words.
//
// A word is defined as a sequence of non-space characters. The words in s will be separated by at least one space.
//
// Return a string of the words in reverse order concatenated by a single space.
//
// Note that s may contain leading or trailing spaces or multiple spaces between two words. The returned string should only have a single space separating the words. Do not include any extra // spaces.
//
// Example 1:
//
// Input: s = "the sky is blue"
// Output: "blue is sky the"
// Example 2:
//
// Input: s = "  hello world  "
// Output: "world hello"
// Explanation: Your reversed string should not contain leading or trailing spaces.
// Example 3:
//
// Input: s = "a good   example"
// Output: "example good a"
// Explanation: You need to reduce multiple spaces between two words to a single space in the reversed string.
//
// Constraints:
//
// 1 <= s.length <= 104
// s contains English letters (upper-case and lower-case), digits, and spaces ' '.
// There is at least one word in s.
func reverseWords(s string) string {
 
    // Разбиваем строку на подстроки по условию
    words := strings.Fields(s)
 
    // Меняем порядок элементов в слайсе классическим методом
    for i, j := 0, len(words)-1; i < j; i, j = i+1, j-1 {
        words[i], words[j] = words[j], words[i]
    }
    
    // Возвращаем строку, полученную после объединения элементов слайса через пробел
    return strings.Join(words, " ")
}

func TestReverseWords(t *testing.T) {
    data := []struct {
        s        string
        expected string
    }{
        {"the sky is blue", "blue is sky the"},
        {"  hello world  ", "world hello"},
        {"a good   example", "example good a"},
    }
 
    for i, datum := range data {
        result := reverseWords(datum.s)
 
        if result != datum.expected {
            t.Errorf(
                "unexpected result for test data index %d (%s), expected [%s], but got [%s]",
                i,
                datum.s,
                datum.expected,
                result,
            )
        }
    }
}