字符串移位包含

题目：给定两个字符串s1和s2，要求判定s2是否能够被s1做循环移位得到的字符串包含。例如，给定s1=AABCD和s2=CDAA,返回true;给定s1=ABCD和s2=ACBD,返回false。

答：

#include "stdafx.h"
#include <iostream>

using namespace std;

//获取next数组的值
void GetNext(const char* pattern, int length, int *next)
{
    int i = 0;
    next[i] = -1;
    int j = -1;
    while (i < length - 1)
    {
        if (-1 == j || pattern[i] == pattern[j])
        {
            i++;
            j++;
            if (pattern[i] != pattern[j])
            {
                next[i] = j;
            }
            else
            {
                next[i] = next[j];
            }
        }
        else
        {
            j = next[j];
        }
    }
}

//KMP算法
bool KMP(const char *src, int slength, const char * pattern, int plength, int *next)
{
    int i = 0;
    int j = 0;
    while (i < slength && j < plength)
    {
        if (-1 == j || src[i] == pattern[j])
        {
            i++;
            j++;
        }
        else
        {
            j = next[j];
        }
    }
    if (j >= plength)
    {
        return true;
    }
    return false;
}

int _tmain(int argc, _TCHAR* argv[])
{
    char src[] = "AABCD";
    char pattern[] = "CDAA";
    int slength =strlen(src);
    int plength = strlen(pattern);
    char *psrc = new char[slength * 2 + 1];
    strcpy(psrc, src);
    strcat(psrc, src);
    *(psrc + slength * 2) = '\0';
    int *next = new int[plength];
    GetNext(pattern, plength, next);
    if (KMP(psrc, slength * 2, pattern, plength, next))
    {
        cout<<"字符串"<<src<<"循环移位可以得到"<<pattern<<endl;
    }
    else
    {
        cout<<"字符串"<<src<<"循环移位得不到"<<pattern<<endl;
    }

    delete [] psrc;
    cout<<endl;
    return 0;
}

运行界面如下：