NC_5_ALL_PATH_SUM

package org.example.interview.practice;

/**
 * @author xianzhe.ma
 * @date 2021/8/21
 */

public class NC_5_ALL_PATH_SUM {

    public static int sumNumbers(TreeNode root) {
        // write code here
        if (root == null) return 0;
        return backtrack(root, 0);
    }

    public static int backtrack(TreeNode root, int sum) {
        if (root == null) return sum;
        // 加入当前结点的值
        sum = sum * 10 + root.val;
        if (root.left == null && root.right == null) {
            // 到叶子结点返回计算的值
            return sum;
        }
        // 未到叶子结点，则往左右子节点继续计算和
        return backtrack(root.left, sum) + backtrack(root.right, sum);
    }

    public static class TreeNode {
        int val = 0;
        TreeNode left = null;
        TreeNode right = null;

        public TreeNode(int val) {
            this.val = val;
        }
    }

    public static void main(String[] args) {
        TreeNode node0 = new TreeNode(4);
        TreeNode node1 = new TreeNode(1);
        TreeNode node2 = new TreeNode(2);
        node0.right = node1;
        node0.left = node2;
        int result = sumNumbers(node0);
        System.out.println(result);

    }
}