二叉树路径总和——Leetcode

 

代码实现:

第一次写的错误代码:

    public boolean hasPathSum(TreeNode root, int targetSum) {
        if (root == null) return false;
        targetSum = targetSum - root.val;
        if (root.left == null && root.right == null){
            if (targetSum == 0){
                return true;
            }
        }
        hasPathSum(root.left,targetSum);
        hasPathSum(root.right,targetSum);
        return false;
    }

第二次改正后：

    public boolean hasPathSum(TreeNode root, int targetSum) {
        if (root == null) return false;
        targetSum = targetSum - root.val;
        if (root.left == null && root.right == null){
            if (targetSum == 0){
                return true;
            }
        }
        return hasPathSum(root.left,targetSum) || hasPathSum(root.right,targetSum);
    }

 对比这两次，希望对递归的理解更加深刻。