kmp 算法

前言: 少 kmp 多学习

0X00 算法板子

831. KMP字符串

感觉还是很难理解

n, s1 = int(input()), input()
m, s2 = int(input()), input()

ne = [0] * (n+1)

# 求出 ne 数组
# ne[i] 表示前后缀中最长的公共串的长度
# 且 ne[i] 又是前缀的后面一位的索引
# j 表示上一次的前缀的后面一位的索引
j = 0
for i in range(2, n+1):
    while j != 0 and s1[i-1] != s1[j]: j = ne[j]
    if s1[i-1] == s1[j]: j += 1
    ne[i] = j


# 开始匹配
j = 0
for i in range(m):
    while j != 0 and s2[i] != s1[j]: j = ne[j]
    if s2[i] == s1[j]: j += 1
    if j == n:
        j = ne[j]
        print(i-n+1, end=" ")