kmp

#include <string.h>

#include <iostream>

void getNext(char* p,int next[])

{

    int i = 0;

    int k = -1;

    next[0] = -1;

    int pLen = strlen(p);

    while(i < pLen - 1) {

        if(k == -1 || p[i] == p[k]) {

            i++;

            k++;

            next[i] = k;

        } else {

            k = next[k];

        }

    }

}

int kmp(char* s,char*p)

{

    int i = 0;

    int j = 0;

    int sLen = strlen(s);

    int pLen = strlen(p);

    int next[pLen];

    getNext(p,next);

    while( i < sLen && j < pLen) {

        if( j == -1 || s[i] == p[j]) {

            i++;

            j++;

        } else {

            j = next[j];

        }

    }

    if( j == pLen) return i - j;

    else return -1;

}

int main(int argc,char** argv)

{    

    char s[] = "bacbababadababacambabacaddababacasdsd";

    char p[] = "ababaca";

    std::cout << "source string is " << s << std::endl;

    std::cout << "pattern string is " << p << std::endl;

    std::cout << kmp(s,p) << std::endl;

}