Merge Two Binary Trees
给两个二叉树, 合并成一个二叉树, 合并的规则是如果一边是null, 就是另一侧是值, 如果两边都不是null就是两个值的和.
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/** * 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 { public TreeNode mergeTrees(TreeNode root1, TreeNode root2) { if(root1 == null && root2 == null) return null; if(root1 == null) return root2; if(root2 == null) return root1; TreeNode root = new TreeNode((root1 == null ? 0 : root1.val) + (root2 == null ? 0 : root2.val)); root.left = mergeTrees(root1.left, root2.left); root.right = mergeTrees(root1.right, root2.right); return root; } } |