dfs burning

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    int maxTime = 0;

    public int amountOfTime(TreeNode root, int start) {
        find(root, start);
        return maxTime;
    }

    public int find(TreeNode root, int target) {
        if (root == null) return -1;

        if (root.val == target) {
            dfs(root, 0); // Start infection from here
            return 1;
        }

        int left = find(root.left, target);
        if (left > 0) {
            dfs(root.right, left+1); // fix: should be left
            maxTime = Math.max(maxTime, left);
            return 1 + left;
        }

        int right = find(root.right, target);
        if (right > 0) {
            dfs(root.left, right+1); // fix: should be right
            maxTime = Math.max(maxTime, right);
            return 1 + right;
        }
        return -1;
    }
    public void dfs(TreeNode root, int time) {
        if (root == null) return;
        maxTime = Math.max(maxTime, time);
        dfs(root.left, time + 1);
        dfs(root.right, time + 1);
    }
}