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 }