404. Sum of Left Leaves

[Shawngbk]

leaf的意思是没有left or right子节点

/**

• Definition for a binary tree node.
• public class TreeNode {
• int val;
• TreeNode left;
• TreeNode right;
• TreeNode(int x) { val = x; }
• } */

public class Solution { public int sumOfLeftLeaves(TreeNode root) { if(root == null) return 0; if(root.left != null && isLeaf(root.left)) return root.left.val + sumOfLeftLeaves(root.right); else return sumOfLeftLeaves(root.left) + sumOfLeftLeaves(root.right); } private boolean isLeaf(TreeNode root) { if(root.left == null && root.right == null) return true; else return false; } }

[Shawngbk]

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