#include <iostream> #include <stack> // 后进先出 using namespace std; int main() { stack<string> strStack; stack<string> outStack; // 备份strStack栈,不影响其继续压栈 int m; string str; cin >> m; for (int i = 1; i <= m;i++) { cin >> str; strStack.push(str); outStack = strStack; cout << "1=" << outStack.top(); outStack.pop(); for (int j = 2; j <= 4;j++) { if (outStack.empty()) { break; } else { cout << " " << j << "=" << outStack.top(); outStack.pop(); } } cout << endl; } return 0; }