完美打印二叉树

参考网址：http://leetcode.com/2010/09/how-to-pretty-print-binary-tree.html

google搜索tree shape print  binary tree，不得不佩服谷歌的精准搜索，这也是很多人选择谷歌的原因。

直接调用printPretty(T->root,1, 0, std::cout);即可

void printBranches(int branchLen, int nodeSpaceLen, int startLen, </span>
                              int nodesInThisLevel, </span>
                                 const deque<binarySearchTree*>& nodesQueue, </span>
                                 ostream& out) </span>
  {
      deque<binarySearchTree*>::const_iterator iter = nodesQueue.begin();
     for (int i = 0; i < nodesInThisLevel / 2; i++) </span>
     {  
         out << ((i == 0) ? setw(startLen-1) : setw(nodeSpaceLen-2)) << "" << ((*iter++) ? "/" : " ");
         out << setw(2*branchLen+2) << "" << ((*iter++) ? "\\" : " ");
     }
   out << endl;
  }


string   intToString(int val)
{  
  stringstream ss;
  ss<<val;
  string str = ss.str();
  return str;
} 


// Print the branches and node (eg, ___10___ )
void printNodes(int branchLen, int nodeSpaceLen, int startLen, int nodesInThisLevel, 
                           const deque<binarySearchTree*>& nodesQueue, ostream& out) 
   {
       deque<binarySearchTree*>::const_iterator iter = nodesQueue.begin();
       for (int i = 0; i < nodesInThisLevel; i++, iter++) 
        {
            out << ((i == 0) ? setw(startLen) : setw(nodeSpaceLen)) << "" << ((*iter && (*iter)->left) ? setfill('_') : 

setfill(' '));
            out << setw(branchLen+2) << ((*iter) ? intToString((*iter)->val) : "");
           out << ((*iter && (*iter)->right) ? setfill('_') : setfill(' ')) << setw(branchLen) << "" << setfill(' ');
        }
      out << endl;
  }


// Print the leaves only (just for the bottom row)
void printLeaves(int indentSpace, int level, int nodesInThisLevel, 
                            const deque<binarySearchTree*>& nodesQueue, ostream& out) 
   {
        deque<binarySearchTree*>::const_iterator iter = nodesQueue.begin();
       for (int i = 0; i < nodesInThisLevel; i++, iter++) </span>
       {
       out << ((i == 0) ? setw(indentSpace+2) : setw(2*level+2)) << ((*iter) ? intToString((*iter)->val) : "");
         }
      out << endl;
   }


// Pretty formatting of a binary tree to the output stream
// @ param
// level  Control how wide you want the tree to sparse </span>
// (eg, level 1 has the minimum space between nodes, while level 2 has a larger space between nodes)
// indentSpace  Change this to add some indent space to the left </span>
// (eg, indentSpace of 0 means the lowest level of the left node will stick to the left margin)
void printPretty(binarySearchTree *root, int level, int indentSpace, ostream& out) </span>
 {
     int h = getHeight(root);
     int nodesInThisLevel = 1;


    int branchLen = 2*((int)pow(2.0,h)-1) - (3-level)*(int)pow(2.0,h-1);  
   // eq of the length of branch for each node of each level
   int nodeSpaceLen = 2 + (level+1)*(int)pow(2.0,h);  
   // distance between left neighbor node's right arm and right neighbor node's left arm
   int startLen = branchLen + (3-level) + indentSpace; 
   // starting space to the first node to print of each level (for the left most node of each level only)


   deque<binarySearchTree*> nodesQueue;
   nodesQueue.push_back(root);
   for (int r = 1; r < h; r++) {
   printBranches(branchLen, nodeSpaceLen, startLen, nodesInThisLevel, nodesQueue, out);
   branchLen = branchLen/2 - 1;
   nodeSpaceLen = nodeSpaceLen/2 + 1;
   startLen = branchLen + (3-level) + indentSpace;
   printNodes(branchLen, nodeSpaceLen, startLen, nodesInThisLevel, nodesQueue, out);


   for (int i = 0; i < nodesInThisLevel; i++) {
   binarySearchTree *currNode = nodesQueue.front();
   nodesQueue.pop_front();
   if (currNode) {  
nodesQueue.push_back(currNode->left);
nodesQueue.push_back(currNode->right);
} else {
nodesQueue.push_back(NULL);
nodesQueue.push_back(NULL);
}
}
nodesInThisLevel *= 2;
}
printBranches(branchLen, nodeSpaceLen, startLen, nodesInThisLevel, nodesQueue, out);
printLeaves(indentSpace, level, nodesInThisLevel, nodesQueue, out);
}