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  • 151. Reverse Words in a String

    package LeetCode_151
    
    /**
     * 151. Reverse Words in a String
     * https://leetcode.com/problems/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.
    
    Example 4:
    Input: s = "  Bob    Loves  Alice   "
    Output: "Alice Loves Bob"
    
    Example 5:
    Input: s = "Alice does not even like bob"
    Output: "bob like even not does Alice"
    
    Constraints:
    1. 1 <= s.length <= 104
    2. s contains English letters (upper-case and lower-case), digits, and spaces ' '.
    3. There is at least one word in s.
    
    Follow up:
    Could you solve it in-place with O(1) extra space?
     * */
    class Solution {
        fun reverseWords(s: String): String {
            //\s+ can handle multi space, but in kotlin, need use toRegex() to fix escape character (ESC)
            val list = s.split("\s+".toRegex())
            val n = list.size
            val result = StringBuilder()
            for(i in n-1 downTo 0){
                result.append(list[i]).append(" ")
            }
            return result.toString().trim()
        }
    }
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  • 原文地址:https://www.cnblogs.com/johnnyzhao/p/13829557.html
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