<span style="font-size:14px;">A B C A B
0 0 0 1 2</span>

算法代码

public static int[] next;

    public static boolean kmp(String str, String dest) {
         for (int i = 0, j = 0; i < str.length(); i ++) {
               while (j > 0 && str.charAt(i) != dest.charAt(j))//iterate to find out the right next position
                    j = next[j - 1];

               if (str.charAt(i) == dest.charAt(j))
                    j ++;

               if (j == dest.length())
                    return true;
          }
          return false;
     }

     public static int[] kmpNext(String str) {
          int[] next = new int[str.length()];
          next[0]  = 0;
          for (int i = 1, j = 0; i < str.length(); i ++) {//j == 0 means the cursor points to nothing.
               //the j here stands for the number of same characters for postfix and prefix, instead of
               //the index of the end of prefix.
                while (j > 0 && strt.charAt(j) != sr.charAt(i))
                    j = next[j - 1]; //watch out here! it's j - 1 here, instead of j

               if (str.charAt(i) == str.charAt(j))
                    j ++;

               next[i] = j;
          }
          return next;
     }