参考博文:
https://blog.csdn.net/v_july_v/article/details/7041827
原文讲的比较全面,加上图解,理解起来也不是很难。
这里采用了优化后的next数组,难点在于next数组的求解,而个人认为next数组求解时递归的部分可能要稍微难理解一点。
具体讲解参考原博,下面是python版本的KMP算法。
class Solution: # 字符串匹配,匹配成功返回目标串中第一次出现的下标,失败返回-1 def KMP(self, target, pattern): next = self.getNext(pattern) print(next) i = j = 0 while i < len(target) and j < len(pattern): # i不存在回溯,匹配则i加1,否则移动模式串j的位置以匹配目标串 if j == -1 or target[i] == pattern[j]: i += 1 j += 1 else: j = next[j] if j == len(pattern): return i-j else: return -1 # 计算next数组 def getNext(self,pattern): next = [0]*len(pattern) next[0] = -1 k = -1 # 前缀结束索引 j = 0 # 后缀结束索引 while j < len(pattern)-1: if k == -1 or pattern[k] == pattern[j]: k += 1 j += 1 if pattern[k] == pattern[j]: next[j] = next[k] else: next[j] = k else: k = next[k] # 寻找更短的后缀 return next if __name__ == '__main__': p = Solution() target = input('Enter the target string:') pattern = input('Enter the pattern string:') while pattern != '-1': print(p.KMP(target, pattern)) pattern = input('Enter the pattern string:')