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beinan/stack_by_queue.cpp

Created November 10, 2015 22:51
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Implement a stack by a single queue
Raw
stack_by_queue.cpp
#include <queue>
class Stack {
queue<int> _q;
public:
// Push element x onto stack.
void push(int x) {
_q.push(x);
}
// Removes the element on top of the stack.
void pop() {
for(int i = 0; i < _q.size() - 1; i++){
int temp = _q.front();
_q.pop();
_q.push(temp);
}
_q.pop();
}
// Get the top element.
int top() {
for(int i = 0; i < _q.size() -1; i++){
int temp = _q.front();
_q.pop();
_q.push(temp);
}
int top = _q.front();
_q.pop();
_q.push(top);
return top;
}
// Return whether the stack is empty.
bool empty() {
return _q.empty();
}
};
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