int func_equal(const char* p, int n, int k)
{
int i = 0; // 0 ~ k-1
int j = n-k; // n-k ~ n-1
while ( i <= k-1 )
{
if ( p[i] != p[j] )
{
return -1;
}
i++;
j++;
}
return 0;
}
void func_get_next(const char* p, int* next)
{
if ( strlen(p) == 0 ) return;
next[0] = -1;
if ( strlen(p) == 1 ) return;
next[1] = 0;
if ( strlen(p) == 2 ) return;
int k = 0;
for ( int n = 2; n < (int)strlen(p); ++n )
{
k = n-1;
while ( k > 0 )
{
if ( 0 == func_equal(p, n, k) )
{
next[n] = k;
break;
}
k--;
}
if ( k <= 0 )
{
next[n] = 0;
}
}
}
int func_string_match(const char* s, const char* p)
{
unsigned int i = 0;
unsigned int j = 0;
int* next = new int[strlen(p)];
func_get_next(p, next);
while ( i < strlen(s) )
{
while ( s[i] == p[j] )
{
i++;
j++;
if ( j == strlen(p) )
{
delete[] next;
return (i - strlen(p));
}
}
j = next[j];
if ( -1 == (int)j )
{
i++;
j = 0;
}
}
delete[] next;
return -1;
}
KMP算法
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