相同的树，迭代解决方案，JavaScript答案

【问题标题】：Same Tree, Iterative Solution, JavaScript相同的树，迭代解决方案，JavaScript
【发布时间】：2019-03-14 19:57:16
【问题描述】：

我需要检查两个给定的二叉树是否相同。这是我写的一个迭代解决方案：

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} p
 * @param {TreeNode} q
 * @return {boolean}
 */

var isSameTree = function(p, q) {
    const nodePair = [p, q]
    const nodes = []

    if(p && q) nodes.push(nodePair) 
    else if (!p && !q) return true
    else return false

    while(nodes.length) {
        const lastNodePair = nodes.pop()

       if(
           (lastNodePair[0].val !== lastNodePair[1].val)
            || (lastNodePair[0].left && !lastNodePair[1].left)
            || (!lastNodePair[0].left && lastNodePair[1].left)
            || (lastNodePair[0].right && !lastNodePair[1].right)
            || (!lastNodePair[0].right && lastNodePair[1].right)
       ) return false

        if(lastNodePair[0].left && lastNodePair[1].left) {
            nodes.push([lastNodePair[0].left, lastNodePair[1].left])   
        }
        else if(lastNodePair[0].right && lastNodePair[1].right) {
            nodes.push([lastNodePair[0].right, lastNodePair[1].right])        
        }
    }
    return true
};

它通过了 57 个测试用例中的 56 个，但这个用例没有通过，应该是 false：

[390,255,2266,-273,337,1105,3440,-425,4113,null,null,600,1355,3241,4731,-488,-367,16,null,565,780,1311,1755,3075,3392,4725,4817,null,null,null,null,-187,152,395,null,728,977,1270,null,1611,1786,2991,3175,3286,null,164,null,null,4864,-252,-95,82,null,391,469,638,769,862,1045,1138,null,1460,1663,null,1838,2891,null,null,null,null,3296,3670,4381,null,4905,null,null,null,-58,null,null,null,null,null,null,null,null,734,null,843,958,null,null,null,1163,1445,1533,null,null,null,2111,2792,null,null,null,3493,3933,4302,4488,null,null,null,null,null,null,819,null,null,null,null,1216,null,null,1522,null,1889,2238,2558,2832,null,3519,3848,4090,4165,null,4404,4630,null,null,null,null,null,null,1885,2018,2199,null,2364,2678,null,null,null,3618,3751,null,4006,null,null,4246,null,null,4554,null,null,null,1936,null,null,null,null,2444,2642,2732,null,null,null,null,null,null,null,4253,null,null,null,null,2393,2461,null,null,null,null,4250,null,null,null,null,2537]

[390,255,2266,-273,337,1105,3440,-425,4113,null,null,600,1355,3241,4731,-488,-367,16,null,565,780,1311,1755,3075,3392,4725,4817,null,null,null,null,-187,152,395,null,728,977,1270,null,1611,1786,2991,3175,3286,null,164,null,null,4864,-252,-95,82,null,391,469,638,769,862,1045,1138,null,1460,1663,null,1838,2891,null,null,null,null,3296,3670,4381,null,4905,null,null,null,-58,null,null,null,null,null,null,null,null,734,null,843,958,null,null,null,1163,1445,1533,null,null,null,2111,2792,null,null,null,3493,3933,4302,4488,null,null,null,null,null,null,819,null,null,null,null,1216,null,null,1522,null,1889,2238,2558,2832,null,3519,3848,4090,4165,null,4404,4630,null,null,null,null,null,null,1885,2018,2199,null,2364,2678,null,null,null,3618,3751,null,4006,null,null,4246,null,null,4554,null,null,null,1936,null,null,null,null,2444,2642,2732,null,null,null,null,null,null,null,4253,null,null,null,null,2461,2393,null,null,null,null,4250,null,null,null,null,2537]

如果可能，我想坚持使用迭代解决方案。

【问题讨论】：

你提供的 2 个数组有什么区别，对我来说看起来一样？
我不明白。样本数据列表不是一棵树吗？并且@Narendra 和2461 在接近尾声时被2393 切换。
@clabe45 它们是树节点值的数组。在 LeetCode 中通过“same tree”搜索可以看到原始问题。
你确定你没有搞砸你的测试用例吗？
只是出于好奇，您为什么要坚持使用迭代解决方案？递归解决方案 - 更紧密地匹配数据结构 - 要简单得多。

标签： javascript data-structures stack binary-tree depth-first-search

【解决方案1】：

您只比较两棵树的左孩子或两棵树的右孩子，因为在比较孩子时您有else if。删除else。因为，如果两棵树中的this.left 和this.right 都不为空，则不会比较正确的孩子，因为那里有else。只比较左边的孩子

    if(lastNodePair[0].left && lastNodePair[1].left) {
        nodes.push([lastNodePair[0].left, lastNodePair[1].left])   
    }
    if(lastNodePair[0].right && lastNodePair[1].right) {
        nodes.push([lastNodePair[0].right, lastNodePair[1].right])        
    }

【讨论】：