将非字母字符替换为空格，使用istringstream、stack实现单词倒排

#include <bits/stdc++.h>
using namespace std;

int main() {
    stack<string> Stack;
    string s;
    getline(cin, s);
    
    for (char& c: s) {
        if (!isalpha(c)) {
            c = ' ';
        }
    }
    istringstream strm(s);
    string word;
    while (strm >> word) {
        Stack.push(word);
    }
    
    while (!Stack.empty()) {
        cout << Stack.top() << " ";
        Stack.pop();
    }
}