字符串匹配 KMP算法

/* description: 字符串匹配 KMP算法 <<编程之法>> P134 author: JasonZhou date: 2016-03-29 */
#include<iostream>
#include <string>
using namespace std;

void calculate_next(string p,int next[])
{
    int len=p.length();
    int  k= -1,j=0;
    next[0]=-1;
    while(j < (len-1))
    {
        if(k == -1 || p[j] == p[k])
        {
            ++k;
            ++j;
            next[j]=k;
        }
        else
        {
            k = next[k];
        }
    }
}


int   KmpSearch(string s1,string s2,int next[])
{
    int i=0;
    int j=0;
    int len1=s1.length();
    int len2=s2.length();


    while (i<len1 && j<len2)
    {
        if (j== -1 ||  s1[i]==s2[j])
        {
            i++;
            j++;
        }
        else
        {
            j=next[j];
        }


    }


    if (j==len2)
    {
        return i-j;
    }
    else
    {
        return -1;
    }


}
int  main()
{
    //原字符串
    string s1="jadfasjfabcdabdabcjdafjakf";
    //要匹配的字符串
    string s2="abcdabdabc";
    int next[10]={0};
    calculate_next(s2,next);
    cout<<"----next array----"<<endl;
    for (int i=0;i<10;i++)
    {
        cout<<next[i]<<" ";
    }
    cout<<endl;
    int point=KmpSearch(s1,s2,next);
    cout<<"---search---"<<endl;

    cout<<s1<<endl;
    for (int j=0;j<point;j++)
    {
        cout<<" ";
    }
    cout<<s2<<endl;
    cout<<"在原字符串匹配成功的位置:";
    cout<<point<<endl;

    return 0;
}

字符串匹配 KMP算法_第1张图片

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