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kmp.java
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kmp.java
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public class KMP {
private String mainText;
KMP(String txt)
{
mainText = txt;
}
public String getText()
{
return mainText;
}
int search(String pattern)
{
boolean jumped = false;
int indexArr[] = buildArr(pattern);
for(int i=0, j=0; i<mainText.length();)
{
if(mainText.charAt(i) == pattern.charAt(j))
{
if (j == pattern.length()-1)
return i-pattern.length()+1;
i++;
j++;
}
else
{
if(i==0 || j==0)
{
//j=0;
i++;
jumped = false;
}
else if (jumped)
{
i++;
jumped = false;
}
else
{
if(j!=0)
j = indexArr[j-1];
jumped = true;
}
}
}
return -1;
}
private int[] buildArr(String pattern)
{
int indexArr[] = new int[pattern.length()];
indexArr[0] = 0;
for(int i=0, j=1; j<pattern.length();)
{
if(pattern.charAt(i) == pattern.charAt(j))
{
indexArr[j] = 1+i;
i++;
j++;
}
else
{
if(i==0)
{
indexArr[j] = 0;
j++;
}
else
i = indexArr[i-1];
}
}
return indexArr;