java求二叉樹的深度

題目

輸入一棵二叉樹，求該樹的深度。從根結點到葉結點依次通過的結點（含根、葉結點）造成樹的一條路徑，最長路徑的長度爲樹的深度。

解題

package demo18;
class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;
    public TreeNode(int val) {
        this.val = val;
    }
}
/**
 * 獲取二叉樹深度
 * @author mengfeiyang
 *
 */
public class Solution2 {
    public int TreeDepth(TreeNode pRoot){
        if(pRoot ==null)
            return 0;
        int nLeft=TreeDepth(pRoot.left);
        int nRight=TreeDepth(pRoot.right);

        return nLeft>nRight?(nLeft+1):(nRight+1);
    }
    
    /**
     * 測試
     * @param args
     */
    public static void main(String[] args) {
    	Solution2 s2 = new Solution2();
    	/**
    	 * 構造二叉樹     
    	 *       1
    	 *      / \
    	 *     2   3
    	 *    / \ / \
    	 *   4  5 6  7
    	 */
		TreeNode root = new TreeNode(1);
		TreeNode left = new TreeNode(2);
		TreeNode right = new TreeNode(3);
		
		TreeNode left_1 = new TreeNode(4);
		TreeNode right_1 = new TreeNode(5);
		TreeNode right_2 = new TreeNode(6);
		TreeNode left_2 = new TreeNode(7);
		
		left.left = left_1;
		left.right = right_1;
		right.left = left_2;
		right.right = right_2;
		
		root.left = left;
		root.right = right;
		
		System.out.println(s2.TreeDepth(root));// 輸出結果爲：3
	}
}