/
binary_search.go
58 lines (48 loc) · 1.24 KB
/
binary_search.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
package main
import (
"fmt"
)
func binarySearch(arr []int, val int) int {
first := 0
last := len(arr) - 1
for first <= last {
mid := first + (last-first)>>1
switch {
case arr[mid] == val:
return mid
case arr[mid] < val:
first = mid + 1
case arr[mid] > val:
last = mid - 1
}
}
// not exist
return -1
}
func binarySearchByRecursion(arr []int, val int, start int) int {
first := 0
last := len(arr) - 1
if first <= last {
mid := first + (last-first)>>1
switch {
case arr[mid] == val:
return mid + start
case arr[mid] < val:
return binarySearchByRecursion(arr[mid+1:], val, mid+1)
case arr[mid] > val:
return binarySearchByRecursion(arr[:mid], val, start)
}
}
// not exist
return -1
}
func main() {
fmt.Println("Welcome to the playground!")
inputSlice := []int{1, 3, 5, 6, 7, 9, 11, 12, 14, 15}
searchItem := 9
searchNotExistItem := 8
fmt.Println("Result for item position:", binarySearch(inputSlice, searchNotExistItem))
fmt.Println("Result for item position:", binarySearch(inputSlice, searchItem))
fmt.Println("Result for item position:", binarySearchByRecursion(inputSlice, searchNotExistItem, 0))
fmt.Println("Result for item position:", binarySearchByRecursion(inputSlice, searchItem, 0))
}