字符串模式匹配KMP算法

package main

import (
    "fmt"
)


func getNext(str string) []int {
    length := len(str)
    next := make([]int, length)
    next[0] = -1
    for i := 1; i < length; i++ {
        j := i - 1
        for j > 0 {
            if str[i-1] == str[next[j]] {
                next[i] = next[j] + 1
                break
            } else {
                j = next[j]
            }
        }
        if j <= 0 {
            next[i] = 0
        }
    }
    for k := 0; k < length; k++ {
        fmt.Print(next[k], "\t")
    }
    return next
}

func kmp(parstr, substr string) int {
    next := getNext(substr)
    lengthp := len(parstr)
    lengths := len(substr)
    i, j := 0, 0
    for i < lengthp && j < lengths {
        if parstr[i] == substr[j] {
            i++
            j++
        } else if next[j] == -1 {
            i++
            j = 0
        } else {
            j = next[j]
        }
    }
    if j < lengths {    
        return -1
    } else {
        return i - lengths
    }
}

func main() {
    fmt.Println(kmp("abaababaafdsbfabcaab", "aababcaab"))
}