01:查找最接近的元素

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 int main(int argc, char *argv[])
 4 {
 5     int n,i,*a,m,t;
 6     int begin,end,mid;
 7     int x,y;
 8     
 9     scanf("%d",&n);
10     a=(int *)malloc(n*sizeof(int));
11     for(i=0;i<n;i++) scanf("%d",&a[i]);
12     
13     scanf("%d",&m);
14     for(i=0;i<m;i++)
15     {
16         scanf("%d",&t);
17         if(a[0]>t) { printf("%d\n",a[0]); continue;}
18         else if(a[n-1]<t) { printf("%d\n",a[n-1]); continue;}
19         
20         begin=0;
21         end=n-1;
22         mid=(begin+end)/2;
23         while(begin<=end)   //while(end-begin>1)
24         {
25             if(a[mid]==t) { printf("%d\n",a[mid]);break;}
26             else 
27             {
28                 if(a[mid]>t)
29                 {
30                     end=mid-1;
31                 }
32                 else 
33                 {
34                     begin=mid+1;
35                 }
36             }
37             mid=(begin+end)/2;
38         }
39         if(a[mid]!=t)
40         {
41             x=abs(a[begin]-t);
42             y=abs(a[end]-t);
43             if(x<y) printf("%d\n",a[begin]);
44             else if(x>y) printf("%d\n",a[end]);
45             else printf("%d\n",(a[begin]<a[end]?a[begin]:a[end]));
46         }
47     }
48     free(a);
49     return 0;
50 }