用两个栈实现队列

class CQueue {
    
public:
    stack<int>InStack;
    stack<int>OutStack;
    CQueue() {
    

    }
    
    void appendTail(int value) {
    
        InStack.push(value);
    }
    
    int deleteHead() {
    
        if(InStack.empty()) 
                return -1;
        if(OutStack.empty())
        {
    
            while(!InStack.empty())
            {
    
                OutStack.push(InStack.top());
                InStack.pop();
            }
        }
        int result=OutStack.top();
        OutStack.pop();
        
        while(!OutStack.empty())
        {
    
            InStack.push(OutStack.top());
            OutStack.pop();
        }
        return result;
    }
};

/** * Your CQueue object will be instantiated and called as such: * CQueue* obj = new CQueue(); * obj->appendTail(value); * int param_2 = obj->deleteHead(); */