[Leetcode] Implement Stack using Queues

Implement Stack using Queues

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 may assume this all operations is valid (for example, no pop or top operations would be called on an empty stack).
• Depending on your language, queue May is not supported natively. You could simulate a queue by using a list or deque (double-ended queue), as long as if you have standard operations of a Q Ueue-which means only push to back ,, pop from front , size and is empty operations is valid.

Credits:
Special thanks to @jianchao. Li.fighter for adding the problem and all test cases.

Water problem.

1 classStack {2 Private:3queue<int> que[2];4     intCur =0;5     6  Public:7     //Push element x onto stack.8     voidPushintx) {9 Que[cur].push (x);Ten     } One  A     //removes the element on top of the stack. -     voidPopvoid) { -          while(Que[cur].size () >1) { theque[1-Cur].push (Que[cur].front ()); - Que[cur].pop (); -         } - Que[cur].pop (); +Cur =1-cur; -     } +  A     //Get the top element. at     intTopvoid) { -          while(Que[cur].size () >1) { -que[1-Cur].push (Que[cur].front ()); - Que[cur].pop (); -         } -         inttop =Que[cur].front (); inque[1-Cur].push (Que[cur].front ()); - Que[cur].pop (); toCur =1-cur; +         returntop; -     } the  *     //Return Whether the stack is empty. $     BOOLEmptyvoid) {Panax Notoginseng         returnque[cur].empty (); -     } the};

[Leetcode] Implement Stack using Queues