二叉樹高度可以採用遞迴計算

public class TreeNode{
	Data value;
	TreeNode left;
	TreeNode right;
	
	TreeNode(Data data,TreeNode left,TreeNode right) {
		this.data = data;
		this.left = left;
		this.right = right;
	}
}

public int getDeep(TreeNode root) {
	if (root == null) {
		return 0;
	} else {
		int left =
 
 getDeep(root.left);
		int right = getDeep(root.right);
		return Math.max(left,right) + 1;
	}
}

二叉樹寬度可以採用計算迭代和遞迴，優先看看迭代計算：

// 從根節點，一層一層的計算寬度，保留最大寬度
public int getWeight(TreeNode root) {
	if (root == null) {
		return 0;
	}
	Queue<TreeNode> queue = new ArrayDeque<>();
	int maxWeight = 1;
 

	queue.add(root);
	// 一層一層迭代
	while(true) {
		int len = queue.size();
		if(len == 0) {
			break;
		}
		// 每一層遍歷所有節點
		while( len >0 ){
			// 獲取並刪除佇列中的頭部節點
			TreeNode t = queue.poll();
			len--;
			// 新增下一層的子節點到佇列
			if(t.left != null){
				queue.add(t.left);
			}
			if(t.right != null){
				queue.add(t.right)
 
;
			}
			maxWeight = Math.max(maxWeight,queue.size());
		}
	}
	return maxWeight;
}

再來看看遞迴演算法：

public int getWeight(TreeNode root) {
	if(root == null){
		return 0;
	}
	int maxWeight = 0;
	if(root.left == null && root.right == null) {
		return 1;
	} else {
		// 遞迴到葉子節點層，計算其寬度，然後迭代到根節點
		maxWeight = Math.max(getWeight(root.left)+getWeight(root.right),maxWeight);
	}
	return maxWeight;
}