用两个栈实现队列功能剑指offer

Posted 2020-12-30 蓝莓派Alex

题目描述：

用两个栈来实现一个队列，完成队列的Push和Pop操作。 队列中的元素为int类型。

程序代码：

【方法一】

 1 class Solution
 2 {
 3 public:
 4 
 5     void push(int node) {
 6         stack1.push(node);
 7 
 8 
 9     }
10 
11     int pop() {
12         int a;
13         if (stack2.size() <= 0){
14             while (stack1.size()>0){
15                 a = stack1.top();
16                 stack2.push(a);
17                 stack1.pop();
18             }
19         }
20         a = stack2.top();
21         stack2.pop();
22 
23         return a;
24 
25 
26     }
27 
28 private:
29     stack<int> stack1;
30     stack<int> stack2;
31 };

【方法二】

 1 class Solution
 2 {
 3 public:
 4     int cou = 0;
 5     void push(int node) {
 6         stack1.push_back(node);
 7         stack2.push_back(cou++);
 8     }
 9 
10     int pop() {
11         int i = 0;
12         while (stack2[i] == -1)
13         {
14             i++;
15         }
16         stack2[i] = -1;
17         return stack1[i];
18     }
19 
20 private:
21     vector <int> stack1;//存数
22     vector <int> stack2;//地址
23 };

测试用例：

 1 int main()
 2 {
 3     Solution fun;
 4     int a[10] = {1,2,3,0,0,4,0,5,0,0};
 5     int i;
 6     for ( i = 0; i < 10; i++)
 7     {
 8         fun.push(a[i]);
 9     }
10     for ( i = 0; i < 10; i++)
11     {
12         cout << " " << fun.pop() /*<< endl*/;
13     }
14     getchar();
15     return 0;
16 }