查找算法

 1 // 递归算法
 2 int BinarySearch(int item, Node *elem, int left, int right)
 3 {
 4     int mid = -1;
 5     if(left <= right) {
 6         mid = (left + right) / 2;
 7         if(elem.val < item) 
 8             mid = BinarySearch(item, elem, (mid + 1), right);
 9         else if(elem.val > item)
10             mid = BinarySearch(item, elem, left, (mid - 1));
11     }
12     return mid;
13 }
14 
15 // 非递归算法
16 int BinarySearch(int item, Node *elem, int len)
17 {
18     int left = 0, right = len - 1, mid = -1;
19     while(left <= right) {
20         mid = (left + right) / 2;
21         if(elem.val < item)
22             left = mid + 1;
23         else if(elem.val > item)
24             right = mid - 1;
25         else
26             return mid;
27     }
28     return NOFOUND;
29 }