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| void getNext(string substr, int next[])
{
int i = 0,j = -1;
next[0] = -1;
while (i<substr.length() - 1)
{
if (j == -1 || substr[i] == substr[j])
{
++i;
++j;
if (substr[i] != substr[j])
{
next[i] = j;
}
else
{
next[i] = next[j];
}
}
else
j = next[j];
}
}
int KMP(string str, string substr)
{
int* next = new int[substr.length()];
getNext(substr, next);
int i = 0,j = 0;
while (i<str.length() && j<substr.length())
{
if (j == -1 || str[i] == substr[j])
{
++i;
++j;
}
else
{
j = next[j];
}
}
if (j >= substr.length())
{
return i - substr.length();
}
return -1;
}
|