Stack 的一些

1. reverse a stack with recursion

void reverse_push(stack<int> &stk, int x)
{
	if(stk.empty())
	{
		stk.push(x);
		return;
	}
	int temp = stk.top();
	stk.pop();
	reverse_push(stk, x);
	stk.push (temp);
}
void reverse(stack<int>& stk)
{
	if(stk.empty())
	{
		cout<<"aaa"<<endl;
		return;
	}
	int temp = stk.top();
	stk.pop();
	cout<<temp<<endl;
	reverse(stk);
	reverse_push(stk, temp);
}

　　

2. 两个栈，调转第一个栈元素的顺序。

void reverse_stack(stack<int> &st1)
{
    stack<int> st2;
    int temp;
    int size = st1.size();
    while(size--)
    {
        temp = st1.top();
        st1.pop();
        int n = size;
        while(n--)
        {
            st2.push(st1.top());
            st1.pop();
        }
        st1.push(temp);
        while(!st2.empty())
        {
            st1.push(st2.top());
            st2.pop();
        }
    }
}