用两个栈实现队列
我的方法:
class Solution { public: void push(int node) { while(!stack2.empty()) { stack1.push(stack2.top()); stack2.pop(); } stack1.push(node); } int pop() { while(!stack1.empty()) { stack2.push(stack1.top()); stack1.pop(); } int n = stack2.top(); stack2.pop(); return n; } private: stack<int> stack1; stack<int> stack2; };
改进了一些:
class Solution { public: void push(int node) { stack1.push(node); } int pop() { int res; if(!stack2.empty()) { res = stack2.top(); stack2.pop(); return res; } else { while(!stack1.empty()) { stack2.push(stack1.top()); stack1.pop(); } res = stack2.top(); stack2.pop(); return res; } } private: stack<int> stack1; stack<int> stack2; };