KMP

void KMPStringSearch(char* pat, char* str) {
    int M = strlen(pat);
    int N = strlen(str);
  
    int lps[M];
    computeLPSArray(pat, M, lps);
  
    int i = 0; 
    int j = 0;
    while (i < N) {
        if (pat[j] == str[i]) {
            j++;
            i++;
        }
  
        if (j == M) {
            printf("Found pattern at index %d ", i - j);
            j = lps[j - 1];
        }
        else if (i < N && pat[j] != str[i]) {
            if (j != 0)
                j = lps[j - 1];
            else
                i = i + 1;
        }
    }
}
  
void computeLPSArray(char* pat, int M, int* lps) {
        int len = 0;
  
    lps[0] = 0;   
       int i = 1;
    while (i < M) {
        if (pat[i] == pat[len]) {
            len++;
            lps[i] = len;
            i++;
        }
        else{
           if (len != 0) {
                len = lps[len - 1];
           }
            else             {
                lps[i] = 0;
                i++;
            }
        }
    }
}