KMP

KMP.cpp

//shihongzhi  -- 2012.3.9
#include <stdio.h>
#include <string.h>

void KMP(char *T, char *P, int *pi)
{
	int tLen = strlen(T);
	int pLen = strlen(P);
	int k = 0;
	for (int i=0; i<tLen; ++i)
	{
		while (k>0 && P[k] != T[i])
		{
			k = pi[k];
		}
		if (P[k] == T[i])
		{
			k++;
		}
		if (k==pLen)
		{
			printf("%d\n", i-pLen+1);
			k = pi[k];
		}
	}
}
//预处理子串
void computePrefix(char *P, int *pi)
{
	int k;
	pi[1] = 0;
	k = 0;
	int len = strlen(P);
	for (int i=1; i<len; ++i)
	{
		while (k>0 && P[k]!=P[i])
		{
			k = pi[k];
		}
		if (P[k] == P[i])
		{
			k++;
		}
		pi[i+1] = k;
	}
}

int main()
{
	char T[] = "bacbababaabcbaba";
	char P[] = "aba";
	int pi[100];
	computePrefix(P, pi);
	KMP(T, P, pi);
	return 0;
}