151 Reverse Words in a String

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本文介绍了一种用于将输入字符串中的单词进行反转的算法，并提供了两种实现方案：一种为尝试性的解决方案，另一种为标准的实现方式。这两种方法都能有效地将字符串中的单词顺序进行反转，同时去除多余的空格。

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1 题目

Given an input string, reverse the string word by word.

Example 1:

Input: "the sky is blue"
Output: "blue is sky the"

Example 2:

Input: "  hello world!  "
Output: "world! hello"
Explanation: Your reversed string should not contain leading or trailing spaces.

Example 3:

Input: "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.

2 尝试解

class Solution {
public:
    string reverseWords(string s) {
        string result = "";
        int index = 0;
        while(index < s.size()){
            if(s[index] == ' ') index++;
            else{
                int count = 0;
                while(index < s.size() && s[index]!=' ' ){
                    index ++;
                    count ++;
                }
                if(result.size() > 0)
                result = s.substr(index-count,count) + ' ' + result;
                else
                result = s.substr(index-count,count) + result;
            }
        }
        return result;
    }
};

3 标准解

class Solution {
public:
    string reverseWords(string s) {
        reverse(s.begin(), s.end());
        int storeIndex = 0;
        for (int i = 0; i < s.size(); i++) {
            if (s[i] != ' ') {
                if (storeIndex != 0) s[storeIndex++] = ' ';
                int j = i;
                while (j < s.size() && s[j] != ' ') { s[storeIndex++] = s[j++]; }
                reverse(s.begin() + storeIndex - (j - i), s.begin() + storeIndex);
                i = j;
            }
        }
        s.erase(s.begin() + storeIndex, s.end());
        return s;
    }
};