二叉树中序遍历

/* function TreeNode(x) {
    this.val = x;
    this.left = null;
    this.right = null;
} */
function Convert(pRootOfTree)
{
    let head = null; //指向链表首节点
    let pre = null; //指向遍历节点的上一节点
    const dfs = (root) => {
        if(!root) return;
        dfs(root.left);
        root.left = pre;
        if(!pre){
             head = root; //root是最小节点
        }else{
            pre.right = root;
        }
        pre = root;
        dfs(root.right);
    }
    dfs(pRootOfTree);
    return head;
}
module.exports = {
    Convert : Convert
};