【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
".
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();
}
}
};