题解 | 二叉树中和为某一值的路径(一)

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param root TreeNode类
     * @param sum int整型
     * @return bool布尔型
     */
    public boolean hasPathSum (TreeNode root, int sum) {
        return hasPathSum(root, sum, 0);
    }
    static public boolean hasPathSum(TreeNode root, int sum, int target) {
        if (root == null) {
            return false;
        }
        if (target + root.val == sum && root.left == null && root.right == null) {
            return true;
        }
        return hasPathSum(root.left, sum, target + root.val) ||
               hasPathSum(root.right, sum, target + root.val);
    }
}