《大话数据结构》读书笔记——8.4.1折半查找

 //c实现
 1 #include "stdafx.h"
 2 #include "stdlib.h"
 3 
 4 
 5 int _tmain(int argc, _TCHAR* argv[])
 6 {
 7     int a[10] = {0,1,3,4,6,7,9,11,12,15};
 8     int low,high,mid,key,flag;
 9     key = 7;flag = -1;
10     low = 0;high = 10;        
11     while(low<high)
12     {
13         mid = (low + high)/2;
14         if(a[mid]>key)
15             high = mid - 1;
16         else if(a[mid]<key)
17             low = mid + 1;
18         else
19         {
20             flag = mid;
21             break;
22         }
23     }    
24     printf("%d",flag);
25     system("pause");
26     return 0;
27 }

//lua实现
 1 function BinarySearch_t(t,key)
 2     local low,flag,high,mid
 3     low = 1
 4     high = #t
 5     flag = -1
 6     while(low<high)
 7     do
 8         mid = (low + high)/2
 9         if(t[mid]>key) then
10             high = mid - 1
11         elseif(t[mid]<key) then
12             low = mid + 1
13         else 
14             flag = mid
15             break
16         end
17     end
18     return flag
19 end
20 --无法运行成功，报错：attempt to compare number with nil
21 --line 9
22 local ta = {0,2,3,4,6,8,9,11,12}
23 --line 24 ↓
24 print(BinarySearch_t(ta,3))