#include<vector>
#include <iostream>
#include<string>
using namespace std;

vector<string> v;


int main() {
    string s;
    getline(cin, s);
    string tmp;
    for (int i = 0; i < s.length(); i++) {
        char c = s[i];
        if (c != ' ') tmp += c;
        else {
            v.push_back(tmp);
            tmp = "";
        } 
    }
    v.push_back(tmp);

    for (auto it = v.rbegin(); it != v.rend(); ++it) {
        cout << *it << " ";
    }
    return 0;
}

用vector来存每一个单词,如果碰到空格就将单词插入到vector中,最后将还没有插入的单词插入,然后反向遍历即可。