KMP模式匹配算法c语言代码

KMP模式匹配算法是一种高效的字符串匹配算法，它通过预处理模式串，构建一个部分匹配表（Next数组），来避免不必要的回溯操作。下面是KMP算法的C语言代码示例：

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

void getNext(char* pattern, int* next) {
    int len = strlen(pattern);
    int i = 0, j = -1;
    next[0] = -1;

    while (i < len) {
        if (j == -1 || pattern[i] == pattern[j]) {
            i++;
            j++;
            next[i] = j;
        } else {
            j = next[j];
        }
    }
}

int kmpSearch(char* text, char* pattern) {
    int textLen = strlen(text);
    int patternLen = strlen(pattern);
    int i = 0, j = 0;
    int* next = (int*)malloc(sizeof(int) * patternLen);

    getNext(pattern, next);

    while (i < textLen && j < patternLen) {
        if (j == -1 || text[i] == pattern[j]) {
            i++;
            j++;
        } else {
            j = next[j];
        }
    }

    free(next);

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

int main() {
    char text[] = "ABABABABCABABABA";
    char pattern[] = "ABABCABAB";

    int index = kmpSearch(text, pattern);

    if (index != -1) {
        printf("Pattern found at index %d\n", index);
    } else {
        printf("Pattern not found\n");
    }

    return 0;
}