// A C program to implement Ukkonen's Suffix Tree Construction
// Here we build generalized suffix tree for two strings
// And then we find longest common substring of the two input strings
class LCS {

  static int MAX_CHAR = 256;
  
  class Node {
    Node children[] = new Node[MAX_CHAR];
  
    //pointer to other node via suffix link
    Node suffixLink;
  
    /*(start, end) interval specifies the edge, by which the
      node is connected to its parent node. Each edge will
      connect two nodes,  one parent and one child, and
      (start, end) interval of a given edge  will be stored
      in the child node. Lets say there are two nods A and B
      connected by an edge with indices (5, 8) then this
      indices (5, 8) will be stored in node B. */
    int start;
    int end;
  
    /*for leaf nodes, it stores the index of suffix for
      the path  from root to leaf*/
    int suffixIndex;
  };
  
  char text[] = new char[100]; //Input string
  Node root = null; //Pointer to root node
  
  /*lastNewNode will point to newly created internal node,
    waiting for it's suffix link to be set, which might get
    a new suffix link (other than root) in next extension of
    same phase. lastNewNode will be set to null when last
    newly created internal node (if there is any) got it's
    suffix link reset to new internal node created in next
    extension of same phase. */
  Node lastNewNode = null;
  Node activeNode = null;
  
  /*activeEdge is represented as input string character
    index (not the character itself)*/
  int activeEdge = -1;
  int activeLength = 0;
  
  // remainingSuffixCount tells how many suffixes yet to
  // be added in tree
  int remainingSuffixCount = 0;
  int leafEnd = -1;
  int rootEnd = null;
  int splitEnd = null;
  int size = -1; //Length of input string
  int size1 = 0; //Size of 1st string
  
  Node newNode(int start, int end) {
    Node node = new Node();
    int i;
    for (i = 0; i < MAX_CHAR; i++)
      node.children[i] = null;
  
    /*For root node, suffixLink will be set to null
      For internal nodes, suffixLink will be set to root
      by default in  current extension and may change in
      next extension*/
    node.suffixLink = root;
    node.start = start;
    node.end = end;
  
    /*suffixIndex will be set to -1 by default and
      actual suffix index will be set later for leaves
      at the end of all phases*/
    node.suffixIndex = -1;
    return node;
  }
  
  int edgeLength(Node n) {
    if(n == root)
      return 0;
    return (n.end) - (n.start) + 1;
  }
  
  int walkDown(Node currNode) {
    /*activePoint change for walk down (APCFWD) using
      Skip/Count Trick  (Trick 1). If activeLength is greater
      than current edge length, set next  internal node as
      activeNode and adjust activeEdge and activeLength
      accordingly to represent same activePoint*/
    if (activeLength >= edgeLength(currNode)) {
      activeEdge += edgeLength(currNode);
      activeLength -= edgeLength(currNode);
      activeNode = currNode;
      return 1;
    }
    return 0;
  }
  
  void extendSuffixTree(int pos) {
    /*Extension Rule 1, this takes care of extending all
      leaves created so far in tree*/
    leafEnd = pos;
  
    /*Increment remainingSuffixCount indicating that a
      new suffix added to the list of suffixes yet to be
      added in tree*/
    remainingSuffixCount++;
  
    /*set lastNewNode to null while starting a new phase,
      indicating there is no internal node waiting for
      it's suffix link reset in current phase*/
    lastNewNode = null;
  
    //Add all suffixes (yet to be added) one by one in tree
    while(remainingSuffixCount > 0) {
  
      if (activeLength == 0) activeEdge = pos; //APCFALZ
  
      // There is no outgoing edge starting with
      // activeEdge from activeNode
      if (activeNode.children == null) {
        //Extension Rule 2 (A new leaf edge gets created)
        activeNode.children = newNode(pos, leafEnd);
  
        /*A new leaf edge is created in above line starting
          from  an existng node (the current activeNode), and
          if there is any internal node waiting for it's suffix
          link get reset, point the suffix link from that last
          internal node to current activeNode. Then set lastNewNode
          to null indicating no more node waiting for suffix link
          reset.*/
        if (lastNewNode != null) {
          lastNewNode.suffixLink = activeNode;
          lastNewNode = null;
        }
      }
      // There is an outgoing edge starting with activeEdge
      // from activeNode
      else
        {
          // Get the next node at the end of edge starting
          // with activeEdge
          Node *next = activeNode.children;
          if (walkDown(next))//Do walkdown
            {
              //Start from next node (the new activeNode)
              continue;
            }
          /*Extension Rule 3 (current character being processed
            is already on the edge)*/
          if (text[next.start + activeLength] == text[pos]) {
                //If a newly created node waiting for it's
                //suffix link to be set, then set suffix link
                //of that waiting node to current active node
                if(lastNewNode != null && activeNode != root)
                  {
                    lastNewNode.suffixLink = activeNode;
                    lastNewNode = null;
                  }
 
                //APCFER3
                activeLength++;
                /*STOP all further processing in this phase
                  and move on to next phase*/
                break;
              }
  
              /*We will be here when activePoint is in middle of
                the edge being traversed and current character
                being processed is not  on the edge (we fall off
                the tree). In this case, we add a new internal node
                and a new leaf edge going out of that new node. This
                is Extension Rule 2, where a new leaf edge and a new
                internal node get created*/
          //      splitEnd = (int*) malloc(sizeof(int));
          //       *splitEnd = next.start + activeLength - 1;
  
              //New internal node
              Node *split = newNode(next.start, splitEnd);
              activeNode.children = split;
  
              //New leaf coming out of new internal node
              split.children = newNode(pos, &leafEnd);
              next.start += activeLength;
              split.children] = next;
  
          /*We got a new internal node here. If there is any
            internal node created in last extensions of same
            phase which is still waiting for it's suffix link
            reset, do it now.*/
          if (lastNewNode != null)
            {
              /*suffixLink of lastNewNode points to current newly
                created internal node*/
              lastNewNode.suffixLink = split;
            }
  
          /*Make the current newly created internal node waiting
            for it's suffix link reset (which is pointing to root
            at present). If we come across any other internal node
            (existing or newly created) in next extension of same
            phase, when a new leaf edge gets added (i.e. when
            Extension Rule 2 applies is any of the next extension
            of same phase) at that point, suffixLink of this node
            will point to that internal node.*/
          lastNewNode = split;
        }
  
      /* One suffix got added in tree, decrement the count of
         suffixes yet to be added.*/
      remainingSuffixCount--;
      if (activeNode == root && activeLength > 0) //APCFER2C1
        {
          activeLength--;
          activeEdge = pos - remainingSuffixCount + 1;
        }
      else if (activeNode != root) //APCFER2C2
        {
          activeNode = activeNode.suffixLink;
        }
    }
  }
  
  void print(int i, int j) {
    int k;
    for (k=i; k<=j && text[k] != '#'; k++)
      printf("%c", text[k]);
    if(k<=j)
      printf("#");
  }
  
  //Print the suffix tree as well along with setting suffix index
  //So tree will be printed in DFS manner
  //Each edge along with it's suffix index will be printed
  void setSuffixIndexByDFS(Node *n, int labelHeight) {
    if (n == null)  return;
  
    if (n.start != -1) //A non-root node
      {
        //Print the label on edge from parent to current node
        //Uncomment below line to print suffix tree
        //print(n.start, *(n.end));
      }
    int leaf = 1;
    int i;
    for (i = 0; i < MAX_CHAR; i++)
      {
        if (n.children[i] != null)
          {
            //Uncomment below two lines to print suffix index
            //   if (leaf == 1 && n.start != -1)
            //     printf(" [%d]\n", n.suffixIndex);
  
            //Current node is not a leaf as it has outgoing
            //edges from it.
            leaf = 0;
            setSuffixIndexByDFS(n.children[i], labelHeight +
                                edgeLength(n.children[i]));
          }
      }
    if (leaf == 1)
      {
        for(i= n.start; i<= *(n.end); i++)
          {
            if(text[i] == '#')
              {
                n.end = (int*) malloc(sizeof(int));
                *(n.end) = i;
              }
          }
        n.suffixIndex = size - labelHeight;
        //Uncomment below line to print suffix index
        // printf(" [%d]\n", n.suffixIndex);
      }
  }
  
  void freeSuffixTreeByPostOrder(Node *n)
  {
    if (n == null)
      return;
    int i;
    for (i = 0; i < MAX_CHAR; i++)
      {
        if (n.children[i] != null)
          {
            freeSuffixTreeByPostOrder(n.children[i]);
          }
      }
    if (n.suffixIndex == -1)
      free(n.end);
    free(n);
  }
  
  /*Build the suffix tree and print the edge labels along with
    suffixIndex. suffixIndex for leaf edges will be >= 0 and
    for non-leaf edges will be -1*/
  void buildSuffixTree() {
    size = strlen(text);
    int i;
    rootEnd = (int*) malloc(sizeof(int));
    *rootEnd = - 1;
  
    /*Root is a special node with start and end indices as -1,
      as it has no parent from where an edge comes to root*/
    root = newNode(-1, rootEnd);
  
    activeNode = root; //First activeNode will be root
    for (i=0; i<size; i++)
      extendSuffixTree(i);
    int labelHeight = 0;
    setSuffixIndexByDFS(root, labelHeight);
  }
 
  int doTraversal(Node *n, int labelHeight, int* maxHeight,
                  int* substringStartIndex) {
    if(n == null)
      {
        return;
      }
    int i=0;
    int ret = -1;
    if(n.suffixIndex < 0) //If it is internal node
      {
        for (i = 0; i < MAX_CHAR; i++) {
          if(n.children[i] != null) {
            ret = doTraversal(n.children[i], labelHeight +
                              edgeLength(n.children[i]),
                              maxHeight, substringStartIndex);
                 
            if(n.suffixIndex == -1)
              n.suffixIndex = ret;
            else if((n.suffixIndex == -2 && ret == -3) ||
                    (n.suffixIndex == -3 && ret == -2) ||
                    n.suffixIndex == -4) {
              n.suffixIndex = -4;//Mark node as XY
              //Keep track of deepest node
              if(*maxHeight < labelHeight) {
                *maxHeight = labelHeight;
                *substringStartIndex = *(n.end) -
                  labelHeight + 1;
              }
            }
          }
        }
      }
    else if(n.suffixIndex > -1 && n.suffixIndex < size1)//suffix of X
      return -2;//Mark node as X
    else if(n.suffixIndex >= size1)//suffix of Y
      return -3;//Mark node as Y
    return n.suffixIndex;
  }
 
  void getLongestCommonSubstring() {
    int maxHeight = 0;
    int substringStartIndex = 0;
    doTraversal(root, 0, &maxHeight, &substringStartIndex);
     
    int k;
    for (k=0; k<maxHeight; k++)
      printf("%c", text[k + substringStartIndex]);
    if(k == 0)
      printf("No common substring");
    else
      printf(", of length: %d",maxHeight);
    printf("\n");
  }
  
  // driver program to test above functions
  int main(int argc, char *argv[]) {
    size1 = 7;
    printf("Longest Common Substring in xabxac and abcabxabcd is: ");
    strcpy(text, "xabxac#abcabxabcd$"); buildSuffixTree();
    getLongestCommonSubstring();
    //Free the dynamically allocated memory
    freeSuffixTreeByPostOrder(root);
 
    size1 = 10;
    printf("Longest Common Substring in xabxaabxa and babxba is: ");
    strcpy(text, "xabxaabxa#babxba$"); buildSuffixTree();
    getLongestCommonSubstring();
    //Free the dynamically allocated memory
    freeSuffixTreeByPostOrder(root);
 
    size1 = 14;
    printf("Longest Common Substring in GeeksforGeeks and GeeksQuiz is: ");
    strcpy(text, "GeeksforGeeks#GeeksQuiz$"); buildSuffixTree();
    getLongestCommonSubstring();
    //Free the dynamically allocated memory
    freeSuffixTreeByPostOrder(root);
 
    size1 = 26;
    printf("Longest Common Substring in OldSite:GeeksforGeeks.org");
    printf(" and NewSite:GeeksQuiz.com is: ");
    strcpy(text, "OldSite:GeeksforGeeks.org#NewSite:GeeksQuiz.com$");
    buildSuffixTree();
    getLongestCommonSubstring();
    //Free the dynamically allocated memory
    freeSuffixTreeByPostOrder(root);
 
    size1 = 6;
    printf("Longest Common Substring in abcde and fghie is: ");
    strcpy(text, "abcde#fghie$"); buildSuffixTree();
    getLongestCommonSubstring();
    //Free the dynamically allocated memory
    freeSuffixTreeByPostOrder(root);
 
    size1 = 6;
    printf("Longest Common Substring in pqrst and uvwxyz is: ");
    strcpy(text, "pqrst#uvwxyz$"); buildSuffixTree();
    getLongestCommonSubstring();
    //Free the dynamically allocated memory
    freeSuffixTreeByPostOrder(root);
 
    return 0;
  }
}