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);
}