1 package main
2
3 import (
4 "fmt"
5 )
6
7
8 func getNext(str string) []int {
9 length := len(str)
10 next := make([]int, length)
11 next[0] = -1
12 for i := 1; i < length; i++ {
13 j := i - 1
14 for j > 0 {
15 if str[i-1] == str[next[j]] {
16 next[i] = next[j] + 1
17 break
18 } else {
19 j = next[j]
20 }
21 }
22 if j <= 0 {
23 next[i] = 0
24 }
25 }
26 for k := 0; k < length; k++ {
27 fmt.Print(next[k], "\t")
28 }
29 return next
30 }
31
32 func kmp(parstr, substr string) int {
33 next := getNext(substr)
34 lengthp := len(parstr)
35 lengths := len(substr)
36 i, j := 0, 0
37 for i < lengthp && j < lengths {
38 if parstr[i] == substr[j] {
39 i++
40 j++
41 } else if next[j] == -1 {
42 i++
43 j = 0
44 } else {
45 j = next[j]
46 }
47 }
48 if j < lengths {
49 return -1
50 } else {
51 return i - lengths
52 }
53 }
54
55 func main() {
56 fmt.Println(kmp("abaababaafdsbfabcaab", "aababcaab"))
57 }
