先进后出——栈

#include <iostream>
#include <string>
#include <stack>

int main(int argc, char* argv[]){
    std::string word;
    std::stack<std::string> stk;
    while(std::cin >> word){
        stk.push(word);
    }
    while(!stk.empty()){
        std::cout << stk.top() << " ";
        stk.pop();
    }
    return 0;
}