题解 | #序列化二叉树#

function TreeNode(x) {
    this.val = x;
    this.left = null;
    this.right = null;
}
function Serialize(pRoot)
{
    if (pRoot === null) return '';
    // 使用队列辅助迭代
    const queue = [pRoot];
    let res = ''
    while(queue.length) {
        let levelCount = queue.length; // 一层的数量
        while(levelCount--) {
            const node = queue.shift(); // 依次取出头节点
            if (node === null) { // 如果未空，则使用 # 
                res+=',#'
            } else {
                res+=',' + node.val; // 否则，拼接数组
                queue.push(node.left); // 将左右节点推出队列中
                queue.push(node.right);
            }
        }
    }
    return res.slice(1);
} 
function Deserialize(s)
{
    if (s === '') return null;
    const sArr = s.split(',')
    const rootVal = sArr.shift();
    const root = new TreeNode(rootVal);
    const nodeQueue = [root];
    while(sArr.length) {
        // 获取父节点
        const node = nodeQueue.shift();
        // 获取节点值
        const nodeLeftVal = sArr.shift();
        const nodeRightVal = sArr.shift();
        // 如果节点不为空
        if (nodeLeftVal !== '#') {
            node.left = new TreeNode(nodeLeftVal);
            nodeQueue.push(node.left)
        }
        
        if (nodeRightVal !== '#') {
            node.right = new TreeNode(nodeRightVal);
            nodeQueue.push(node.right)
        }
    }
    
    return root;
}
module.exports = {
    Serialize : Serialize,
    Deserialize : Deserialize
};