Kmp算法 java实现
时间: 2023-11-10 19:00:08 浏览: 48
KMP算法(Knuth-Morris-Pratt算法)是一种用于字符串匹配的算法,它可以在较短的时间内找到一个字符串在另一个字符串中的所有出现位置。下面是KMP算法的Java实现:
```java
public class KMP {
public static void main(String[] args) {
String text = "ABABDABACDABABCABAB";
String pattern = "ABABCABAB";
int[] next = buildNext(pattern);
int index = kmpSearch(text, pattern, next);
if (index != -1) {
System.out.println("Pattern found at index " + index);
} else {
System.out.println("Pattern not found");
}
}
private static int[] buildNext(String pattern) {
int[] next = new int[pattern.length()];
next[0] = -1;
int i = 0, j = -1;
while (i < pattern.length() - 1) {
if (j == -1 || pattern.charAt(i) == pattern.charAt(j)) {
i++;
j++;
next[i] = j;
} else {
j = next[j];
}
}
return next;
}
private static int kmpSearch(String text, String pattern, int[] next) {
int i = 0, j = 0;
while (i < text.length() && j < pattern.length()) {
if (j == -1 || text.charAt(i) == pattern.charAt(j)) {
i++;
j++;
} else {
j = next[j];
}
}
if (j == pattern.length()) {
return i - j;
} else {
return -1;
}
}
}
```