题解 | #二叉树根节点到叶子节点的所有路径和#

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 * }
 */
public static  int sum=0;
public  static Stack<TreeNode> stack=new Stack<>();
public class Solution {
    /**
     * 
     * @param root TreeNode类 
     * @return int整型
     */
     public static  int sum=0;
    public  static Stack<TreeNode> stack=new Stack<>();
    public int sumNumbers (TreeNode root) {
        // write code here
        // write code here
        if(root==null){
            return 0;
        }
        stack.push(root);
        TreeNode left=root.left;
        if (left!=null){
            sumNumbers(left);
        }

        TreeNode right=root.right;
        if (right!=null){
            sumNumbers(right);
        }
        if (root.left==null && root.right==null){
            double aa=stack.pop().val;
            sum=(int)(sum+aa*Math.pow(10.0,0));
            int i=stack.size();
            for (TreeNode binaryNode : stack) {
                sum=(int)(sum+binaryNode.val*Math.pow(10.0,i));
                i--;
            }
            return sum;
        }
        stack.pop();
        return sum;
    }
}