Problem description: Implement a stack using two queues.
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/* The structure of the class is class QueueStack{ private: queue<int> q1; queue<int> q2; public: void push(int); int pop(); }; */ /* The method push to push element into the stack */ void QueueStack :: push(int x) { // Your Code int t; if(q1.size()==0 && q2.size()==0) { q1.push(x); return; } if(q1.size()==0) { q1.push(x); while(q2.size()) { t=q2.front(); q2.pop(); q1.push(t); } } else if(q2.size()==0) { q2.push(x); while(q1.size()) { t=q1.front(); q1.pop(); q2.push(t); } } } /*The method pop which return the element poped out of the stack*/ int QueueStack :: pop() { // Your Code int t; if(q1.size()==0 && q2.size()==0) return -1; if(q1.size()==0) { t=q2.front(); q2.pop(); return t; } if(q2.size()==0) { t=q1.front(); q1.pop(); return t; } } |