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KMP.cpp
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KMP.cpp
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/*
@author Sukeesh
Knuth Morris Prat Algorithm
*/
ll lps[1000010];
void buildlps(string str){
lps[0] = 0;
ll i, j;
i = 0;
j = 1;
while(i<str.sz && j<str.sz){
if(str[i] == str[j]){
lps[j] = i + 1;
j ++;
i ++;
}
else{
if(i!=0) {
i = lps[i-1];
}
else{
lps[j] = 0;
j ++;
}
}
if(j == str.sz){
break;
}
}
}
void kmp(string pattern, string text){
ll i, j, k;
memset(lps, 0, sizeof(lps));
buildlps(pattern);
i = 0 , j = 0;
while( i < text.sz ){
if(pattern[j] == text[i]){
j++;
i++;
}
if(j == pattern.sz){
cout << i-j << endl;
j = lps[j-1];
}
else if( i < text.sz && pattern[j] != text[i] ){
if(j!=0){
j = lps[j-1];
}
else{
i++;
}
}
}
cout << endl;
}