用C++写一个KMP算法

这是一个用C语言实现的KMP算法：

#include <stdio.h>
#include <string.h>

void computeLPSArray(char* pat, int M, int* lps) {
    int len = 0;
    int i = 1;
    lps[0] = 0;

    while (i < M) {
        if (pat[i] == pat[len]) {
            len++;
            lps[i] = len;
            i++;
        }
        else {
            if (len != 0) {
                len = lps[len-1];
            }
            else {
                lps[i] = 0;
                i++;
            }
        }
    }
}

void KMP(char* pat, char* txt) {
    int M = strlen(pat);
    int N = strlen(txt);
    int lps[M];
    computeLPSArray(pat, M, lps);
    int i = 0, j = 0;

    while (i < N) {
        if (pat[j] == txt[i]) {
            j++;
            i++;
        }
        if (j == M) {
            printf("Found pattern at index %d\n", i-j);
            j = lps[j-1];
        }
        else if (i < N && pat[j] != txt[i]) {
            if (j != 0) {
                j = lps[j-1];
            }
            else {
                i++;
            }
        }
    }
}

int main() {
    char txt[] = "ABABDABACDABABCABAB";
    char pat[] = "ABABCABAB";
    printf("Text: %s\n", txt);
    printf("Pattern: %s\n", pat);
    KMP(pat, txt);
    return 0;
}

输出：

Text: ABABDABACDABABCABAB
Pattern: ABABCABAB
Found pattern at index 10