C++实现字符串匹配KMP算法

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1. 概述

Kmp算法的介绍及思想参阅下面两篇文章：
字符串匹配KMP算法
算法）通俗易懂的字符串匹配KMP算法及求next值算法

2. 代码实现

int cTest::findstr1(const char *src, const char *des)
{
    int srlen = strlen(src);
    int delen = strlen(des);
    int i = 0, j = 0, k = 0;
    for (int i = 0; i <= srlen - delen; i++)
    {
        /* code */
        for (k = i, j = 0; j < delen; ++k, ++j)
        {
            /* code */
            if (src[k] != des[j])
                break;
        }
        if (j >= delen)
            return i;
    }
    return -1;
}
void cTest::subNext_kmp(const char *des, int *next)
{
    next[0] = -1;
    int i = 0, k = -1;
    while (des[i] != '\0')
    {
        /* code */
        if (k == -1 || des[k] == des[i])
            next[++i] = ++k;
        else
            k = next[k];
    }
}
int cTest::findstr2(const char *src, const char *des, int* next)
{
    int slen = strlen(src);
    int dlen = strlen(des);
    int i = 0, j = 0;
    while (i < slen && j < dlen)
    {
        /* code */
        if (j==-1 || src[i] == des[j])
        {
            ++i;
            ++j;
        }
        else
            /* code */
            j = next[j];
    }
    if (des[j] == '\0')
        return i - j;
    return -1;
}

3. 代码测试

int main(int argc, char* argv[])
{
    char s[] = "abcabaaaabaabcac";
    char p[] = "abaabcac";
    cout << ctestptr.findstr1(s, p) << endl;
    //shared_ptr next(new int[sizeof(p)],[](int* p){delete[] p;});
    int *next = (int *)malloc(sizeof(int) * sizeof(p));
    ctestptr.subNext_kmp(p, next);
    for (int i = 0; i < strlen(p); ++i)
        cout << next[i];
    cout << endl;
    cout << ctestptr.findstr2(s, p, next) << endl;
    free(next);
}