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 <= 104s contains English letters (upper-case and lower-case), digits, and spaces ' '.s.
Follow-up: If the string data type is mutable in your language, can you solve it in-place with O(1) extra space?
class Solution {
public:
string reverseWords(string s) {
stringstream ss(s);
string word, res="";
vector<string> sentence;
while(ss >> word)
sentence.push_back(word);
reverse(sentence.begin(), sentence.end());
for(auto word:sentence)
res+=word+" ";
res.pop_back();
return res;
}
};