617. 合并二叉树

题目

题解一：递归

  /*** 递归* @param root1* @param root2* @return*/public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {//结束条件if (root1 == null) {return    root2;}      //结束条件if (root2 == null) {return    root1;}//两节点数值相加TreeNode mer = new TreeNode(root1.val+root2.val);//计算左子树mer.left = mergeTrees(root1.left,root2.left);//计算右子树mer.right = mergeTrees(root1.right,root2.right);//返回节点return mer;}

题解二