描述

已知两颗二叉树，将它们合并成一颗二叉树。合并规则是：都存在的结点，就将结点值加起来，否则空的位置就由另一个树的结点来代替。例如：

两颗二叉树是:

链接

BM32 合并二叉树 Nowcoder

示例

{1,3,2,5},{2,1,3,#,4,#,7} => {3,4,5,5,4,#,7}
{1},{} => {1}

题解

/*
 * function TreeNode(x) {
 *   this.val = x;
 *   this.left = null;
 *   this.right = null;
 * }
 */
/**
 * 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 t1 TreeNode类
 * @param t2 TreeNode类
 * @return TreeNode类
 */
function mergeTrees(t1, t2) {
    // write code here

    function go(_t1, _t2, _nt) {
        _nt.val = (_t1?.val || 0) + (_t2?.val || 0);

        if (_t1?.left || _t2?.left) {
            _nt.left = new TreeNode();
            go(_t1?.left, _t2?.left, _nt.left);
        }

        if (_t1?.right || _t2?.right) {
            _nt.right = new TreeNode();
            go(_t1?.right, _t2?.right, _nt.right);
        }
    }

    let nt = new TreeNode();
    let root = nt;
    go(t1, t2, nt);
    return root;
}
module.exports = {
    mergeTrees: mergeTrees,
};