数据结构-1

#include <iostream>
#include <stdio.h>
using namespace std;

#define MaxSize 51
 struct String
{

    int len;
    char* crr;
    int GetLength()
    {
        len = 0;
        for (int i = 0; i < len; i++)
        {

            if (crr[i] == ‘\0‘)
                break;
            len++;
        }
        return len;
    }
    int GetLength(char c[])
    {
        len = 0;
        for (int i = 0; i < len; i++)
        {

            if (c[i] == ‘\0‘)
                break;
            len++;
        }
        return len;
    }
    void Init(char c[])
    {
        len = 0;
        crr = (char*)malloc(MaxSize);

        for (int i = 0; i < MaxSize; i++)
        {

            if (c[i] == ‘\0‘)break;
            crr[i] = c[i];
            len++;
        }

    }
    void Free()
    {
        delete(crr);
    }
    void StrCopy(String* a)//把a的值拷贝到自身
    {
        for (int i = 0; i <a->len; i++)
        {
            crr[i] = a->crr[i];
        }
    len = a->len;
    }
    void ConcatStr(String* a)//把目标连到后面去
    {
        int oldlen = len;
        len = len + a->len;
        crr[len] = ‘\0‘;
        for (int i = 0; i < MaxSize; i++)
        {
            if (crr[oldlen+i] == ‘\0‘)break;
            crr[oldlen + i] = a->crr[i];
        }
    }
    int KMP(String* a)//kmp就是模式匹配的一种优化性算法
    {
        char* arr = (char*)malloc(sizeof(a->len));
        for (int i = 0; i < a->len;i++)
            arr[i] = 0;
        int j = 0;
        for (int i = 1; i < a->len  ; i++)
        {
            if (a->crr[j] == a->crr[i])
            {
                j++;
                arr[i] = j;
            }
            else
            {
                j = arr[j];//arr[j]中存放的数据的意义是：从开始往后数，已经匹配的个数，所以直接还原j为该值
            }
        }
        for (int i = 0; i < a->len; i++)cout << (int)arr[i] << " "; cout << endl;//输出看看
        int ret = 0;
        j = 0;
        for (int i = 0; i < len; i++)//看每一个数
        {
            if (crr[i] == a->crr[j])
            {
                j++;
                if (j == a->len)
                {
                    ret = i-a->len+1;
                    break;
                }
            }
            else//一个都没有匹配的
            {
                if (j != 0)
                 {
                    int move = (j - arr[j - 1]);
                    j -= move; i--;
                    cout << move << "步" << endl;
                }
            }
        }
        return ret;
    }
    void Show()
    {
        for (int i = 0; i < len; i++)
            cout << crr[i]; 
        cout << endl;
    }

};



int main()
{
    //bbc abcdab abcdabcdabde
    char* a = (char*)"bbc abcdab abcdabcdabde";
    String str;
    str.Init(a);
    cout << "str = ";
    str.Show();
    cout << endl;

    String str2;
    str2.Init((char*)"abcdabd");
    //str2.StrCopy(&str);

    cout << "str2 = ";
    str2.Show();
    cout << endl;
    //str.ConcatStr(&str2);


    cout<<endl;
    cout<<"第一次出现该子串的位置在"<<str.KMP(&str2);
    return 0;
}