LeetCode || Implement Queue using Stacks

class Queue {
public:
// Push element x to the back of queue.
void push(int x) {
s1.push(x);
}

// Removes the element from in front of queue.
void pop(void) {
if(s2.size() == 0)
{
while(s1.size()!=0)
{
s2.push(s1.top());
s1.pop();
}
}
s2.pop();
}

// Get the front element.
int peek(void) {
if(s2.size() == 0)
{
while(s1.size()!=0)
{
s2.push(s1.top());
s1.pop();
}
}
return s2.top();
}

// Return whether the queue is empty.
bool empty(void) {
if(s1.size() == 0 && s2.size() == 0)
return true;
return false;
}

stack<int> s1;
stack<int> s2;
};