《微軟面試題》設計包含min函數的棧

設計包含min函數的棧。
定義棧的資料結構，要求添加一個min函數，能夠得到棧的最小元素。

要求函數min、push以及pop的時間複雜度都是O(1)。

代碼如下：

stack.h

#pragma once#include <assert.h>//simulation stack DataStructtemplate<typename T>class Node {public:Node(T t){data = t;pre = NULL;}T data;Node * pre;bool operator >(const T & t){if (data >= t.data){return true;}return false;}};template<typename T>class Stack{public:Stack(){cur = NULL;//pre = NULL;}Node<T> * cur;void pushback(Node<T> * node){node->pre = cur;Node<T> * tmp = cur;cur = node;cur->pre = tmp;}void popback(){Node<T> * tmp = cur->pre->pre;cur = cur->pre;cur->pre = tmp;}Node<T> * min(int destMin){while(cur == NULL || cur->pre != NULL){if (cur->data >= cur->pre->data){cur =cur->pre;}else{cur->pre = cur->pre->pre;}}assert(cur != NULL);if (cur->data != destMin){assert(0);}return cur;}};

man.cpp

#include "stack.h"#include "stdlib.h"#include <time.h>typedef Node<int> _node;typedef Stack<int> _stack;int GetMin(int *num,int len){for (int i=0;i<len;i++){for (int j=len-1;j>i;j--){if (num[i] > num[j]){int tmp = num[i];num[i] = num[j];num[j] = tmp;}}}return num[0];}int _tmain(int argc, _TCHAR* argv[]){_stack mystack;srand(time(NULL));//int a[10]={0};int a[10]={6,1,27,60,24,56,57,58,90,87};for (int i=0;i<10;i++){int tmp = rand()%100;//(i+10)%3;//int tmp = a[i];_node * p = new _node(tmp);printf("%d,",tmp);a[i] = tmp;mystack.pushback(p);}//use pop check minint _min = GetMin(a,10);//printf("\ndest min=%d\n",_min);_node * p = mystack.min(_min);if (p != NULL){printf("\nmin node.data=%d\n",p->data);}assert(_min == p->data);getchar();return 0;}

cpp通過 冒泡排序檢查最小值 和 stack.getmin 比較。