Idea: This
question is to use the idea of a stack to do it. One stack is used to enter the number, and then when you want to output a number, you only need to see if the other stack has a number, if not, put the stack 1 The number is put into stack 2, and stack 2 is equivalent to the element placed in the queue.
Code:
class CQueue {
public:
CQueue() {
}
void appendTail(int value) {
st1.push(value);
return ;
}
int deleteHead() {
if(st1.size()==0 && st2.size()==0 ) return -1;
if(st2.size()){
int t = st2.top();
st2.pop();
return t;
}else{
while(!st1.empty()){
st2.push(st1.top());
st1.pop();
}
int t = st2.top();
st2.pop();
return t;
}
return 0;
}
private:
stack<int> st1,st2;
};
/**
* Your CQueue object will be instantiated and called as such:
* CQueue* obj = new CQueue();
* obj->appendTail(value);
* int param_2 = obj->deleteHead();
*/