56 lines
1.4 KiB
Go
56 lines
1.4 KiB
Go
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/*
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* @Author : huangzj
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* @Time : 2021/2/24 13:19
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* @Description：KMP字符串匹配算法，参考地址：https://www.cnblogs.com/en-heng/p/5091365.html
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* http://www.ruanyifeng.com/blog/2013/05/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm.html
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*/
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package stringMatch
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func KmpMatch(allString string, match string) int {
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next := getNext(match)
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i := 0 //被匹配的字符串下标
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j := 0 //模式匹配字符串下标
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sLength := len(allString) - 1
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mLength := len(match) - 1
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for i <= sLength && j <= mLength {
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if j == -1 || allString[i] == match[j] {
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j++
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i++
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} else {
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j = next[j]
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}
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}
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if j == len(match) {
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return i - j
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}
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return -1
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}
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//失配表函数构建（部分匹配函数）
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func getNext(match string) []int {
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next := make([]int, len(match))
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next[0] = -1
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i := 0
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j := -1
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mLength := len(match) - 1
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for i < mLength {
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//处理两种情况： 1.数组第一个数是-1 2. match对应位置字符相等的情况
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if j == -1 || match[i] == match[j] {
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//如果这里是数组第一个数的时候,下标要往后移动
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//如果这里是数组相等的情况，要比较下一个相应的字符，所以下标需要往后移动，而next需要在上一个的基础上去做+1操作
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i++
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j++
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next[i] = j
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} else {
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//如果匹配过程中，出现对应不上的情况，也就是说 match[i] != match[j],
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j = next[j]
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}
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}
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return next
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}
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