1
这是我执行KMP字符串匹配算法。 当我检查pi阵列,它存储0,1,2,3,4,5,6。但根据算法书它应该是0,0,1,2,3,0,1。我的代码也给出了正确的结果。我不明白为什么会发生这种情况,或者我做错了什么?如果是这样,请纠正我。KMP字符串匹配算法:辅助阵列输出
谢谢。
#include<iostream>
#include<string>
#include<string.h>
using namespace std;
int* ComputePrefix(char P[])
{
size_t m = strlen(P);
int *pi = new int[m];
pi[0] = 0;
int k = 0;
for(int q =0; q < m; q++)
{
if(k > 0 && P[k+1] != P[q])
k = pi[k];
if(P[k+1] == P[q])
{
pi[q] = k;
k = k + 1;
}
pi[q]=k;
}
return (pi);
}
void KMP_Matcher(char T[], char P[])
{
size_t n = strlen(T);
size_t m = strlen(P);
int *pi = new int[m];
pi = ComputePrefix(P);
cout<<endl;
int q =0;
for (int i = 0; i <= n; i++)
{
if(q > 0 && P[q] != T[i])
{
q = pi[q - 1];
}
else if(P[q] == T[i])
{
if(q == m-1)
{
cout<<"Shift occurs at : "<< i-q <<endl;
q = pi[q];
}
else q = q + 1;
}
else q++;
}
}
int main()
{
char T[] = "abababacaba";
char P[] = "ababaca";
KMP_Matcher(T,P);
return 0;
}