LeetCode: Reverse Words in a String [151]

【题目】

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

For example,
Given s = "the sky is blue",
return "blue is sky the".

click to show clarification.

Clarification:

• What constitutes a word?
  A sequence of non-space characters constitutes a word.
• Could the input string contain leading or trailing spaces?
  Yes. However, your reversed string should not contain leading or trailing spaces.
• How about multiple spaces between two words?
  Reduce them to a single space in the reversed string.

【题意】

    给定一个字符串，按单词反转

【思路】

    现切分字符串，然后反向拼接

【代码】

class Solution {public:    void reverseWords(string &s) {        stack<string> words;int start = -1;//记录单词开始的位置for(int i=0; i<s.length(); i++){if(s[i]==' '){if(i!=0 && s[i-1]!=' '){//一个单词结束words.push(s.substr(start, i-start));start = -1;}}else{if(i==0 || s[i-1]==' '){start = i;}}}if(start!=-1)words.push(s.substr(start, s.length()-start));//拼接成反向单词s = "";int count=0;while(!words.empty()){count++;if(count==1)s+=words.top();else s+=" "+words.top();words.pop();}    }};