由 dawei 可能以故事形式：如从第一层到第十层电梯每层停一次，如何找到第二个大的钻石
?1?#include<stdio.h>
??2?#include<assert.h>
??3?#define?MINNUMBER?-32768
??4?int?find_sec_max(int?arr[],int?size)
??5?{
??6?????assert(arr);
??7?????int?maxnumber=arr[0];
??8?????int?sec_max=MINNUMBER;
??9?????int?i=0;
?10?????for(i=1;i<size;++i)
?11?????{
?12?????????if(arr[i]>maxnumber)
?13?????????{
?14?????????????sec_max=maxnumber;
?15?????????????maxnumber=arr[i];
?16?????????}
?17?????????else
?18?????????{
?19?????????????if(arr[i]>sec_max)
?20?????????????????sec_max=arr[i];
?21?????????}
?22?????}
?23?????return?sec_max;
?24?}
?25?int?main()
?26?{
?27?????int?arr[10]={3,2,4,5,6,7,8,9,10};
?28?????printf("In?arr,the?second?max:?%d\n",find_sec_max(arr,10));
?29?????return?0;
?30?}
判断单链表是否带环？
?1?#include<stdio.h>
??2?struct?LinkNode
??3?{
??4?????char?val;
??5?????LinkNode*?next;
??6?};??
??7?bool?check(const?LinkNode*?head)
??8?{
??9?????if(head==NULL)
?10?????????return?false;
?11?????LinkNode*?low=head,*fast=head->next;
?12?????while(fast&&fast->next)
?13?????{???
?14?????????low=low->next;
?15?????????fast=fast->next->next;
?16?????????if(low==fast)
?17?????????????return?true;
?18?????}???????
?19?????return?false;
?20?}
找出两个数中最大的一个：有两个int变量A和B,请不要使用if,?:和switch或其他判断语句，找出两个数中最大的一个。
方案一：
int?max=((a+b)+abs(a-b))/2;
方案二：
int?c=a-b; c=unsigned(c)>>(sizeof(int)*8-1);
写一个函数返回1+2+3+….+n的值(假定结果不会超过长整型变量的范围)
int?sum(int?n)
{
????return?((long)1+n)*n/2;
}