题解 | #堆栈的使用#
堆栈的使用
https://www.nowcoder.com/practice/e91982a145944ceab6bb9a4a508e0e26
#include<iostream> #include<stack> using namespace std; stack<int>ss; int main(){ int n,b;char a; while(cin>>n){for(int i=0;i<n;i++){ cin>>a; if(a=='A'){ if(ss.empty())cout<<'E'<<endl;else cout<<ss.top()<<endl; }else if(a=='P') {cin>>b;ss.push(b);} else if(a=='O'){if(!ss.empty())ss.pop();} } } }