用Java实现kmp算法

Java实现KMP算法的详细步骤如下：
1、初始化next数组：next[1] = -1，next[i] = 0（2≤i≤m）
2、从第i个字符开始，计算next[i]
3、当s[i] == s[k]，则next[i+1] = k+1；
4、当s[i] != s[k]，则查找next[k]，让k = next[k]，重复第3步
5、当k = -1，则让next[i+1] = 0;
6、输出next数组，完成KMP算法的实现。

相关问题

请用java实现 kmp 算法

以下是Java实现的KMP算法代码：

public class KMP {
    public static int[] getNext(String pattern) {
        int len = pattern.length();
        int[] next = new int[len];
        next[0] = -1;
        int i = 0, j = -1;
        while (i < len - 1) {
            if (j == -1 || pattern.charAt(i) == pattern.charAt(j)) {
                i++;
                j++;
                next[i] = j;
            } else {
                j = next[j];
            }
        }
        return next;
    }

    public static int kmpSearch(String text, String pattern) {
        int[] next = getNext(pattern);
        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;
    }

    public static void main(String[] args) {
        String text = "ABCABCABCABCABCABD";
        String pattern = "ABCABD";
        int index = kmpSearch(text, pattern);
        if (index != -1) {
            System.out.println("Pattern found at index " + index);
        } else {
            System.out.println("Pattern not found");
        }
    }
}

Java实现kmp算法

public class KMP {
private int[] next;

public int[] getNext(String pattern) {
int length = pattern.length();
int[] next = new int[length];
next[0] = -1;

int i = 0;
int j = -1;
while (i < length - 1) {
if (j == -1 || pattern.charAt(i) == pattern.charAt(j)) {
i++;
j++;
next[i] = j;
} else {
j = next[j];
}
}

return next;
}

public int kmp(String str, String pattern) {
int[] next = getNext(pattern);

int i = 0;
int j = 0;
int sLength = str.length();
int pLength = pattern.length();
while (i < sLength && j < pLength) {
if (j == -1 || str.charAt(i) == pattern.charAt(j)) {
i++;
j++;
} else {
j = next[j];
}
}

if (j == pLength) {
return i - j;
} else {
return -1;
}
}
}