Description:
Implement the following operations of a stack using queues.
push(x) -- Push element x onto stack.pop() -- Removes the element on top of the stack.top() -- Get the top element.empty() -- Return whether the stack is empty.
Notes:
You must use only standard operations of a queue -- which means only push to back, peek/pop from front, size, and is empty operations are valid.Depending on your language, queue may not be supported natively. You may simulate a queue by using a list or deque (double-ended queue), as long as you use only standard operations of a queue.You may assume that all operations are valid (for example, no pop or top operations will be called on an empty stack).
Solution:
class Stack {
private:
queue<int> q;
public:
// Push element x onto stack.
void push(int x) {
q.push(x);
for (int i = 0; i < q.size()-1; ++i) {
q.push(q.front());
q.pop();
}
}
// Removes the element on top of the stack.
void pop() {
q.pop();
}
// Get the top element.
int top() {
return q.front();
}
// Return whether the stack is empty.
bool empty() {
return q.empty();
}
};
转载于:https://www.cnblogs.com/deofly/p/implement-stack-using-queues.html
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