golang binarySearch 

 1 func binarySearch(nodes []*node, word Text) (int, bool) {
 2     start := 0
 3     end := len(nodes) - 1
 4  
 5     // 特例：
 6     if len(nodes) == 0 {
 7         // 当slice为空时，插入第一位置
 8         return 0, false
 9     }
10     compareWithFirstWord := bytes.Compare(word, nodes[0].word)
11     if compareWithFirstWord < 0 {
12         // 当要查找的元素小于首元素时，插入第一位置
13         return 0, false
14     } else if compareWithFirstWord == 0 {
15         // 当首元素等于node时
16         return 0, true
17     }
18     compareWithLastWord := bytes.Compare(word, nodes[end].word)
19     if compareWithLastWord == 0 {
20         // 当尾元素等于node时
21         return end, true
22     } else if compareWithLastWord > 0 {
23         // 当尾元素小于node时
24         return end + 1, false
25     }
26  
27     // 二分
28     current := end / 2
29     for end-start > 1 {
30         compareWithCurrentWord := bytes.Compare(word, nodes[current].word)
31         if compareWithCurrentWord == 0 {
32             return current, true
33         } else if compareWithCurrentWord < 0 {
34             end = current
35             current = (start + current) / 2
36         } else {
37             start = current
38             current = (current + end) / 2
39         }
40     }
41     return end, false
42 }

 

posted on 2015-03-27 11:12  rojas  阅读(296)  评论(0)    收藏  举报