94

94. 二叉树的中序遍历

https://leetcode-cn.com/problems/binary-tree-inorder-traversal/

• [x] iteration

• [x] recursion

• [ ] morris

• iteration

var inorderTraversal = function(root) {
    let stack = [];
    let res = [];
    while(root !== null || stack.length){
        while(root !== null){
            stack.push(root);
            root = root.left;
        }
        root = stack.pop();
        res.push(root.val);
        root = root.right;
    }
    return res;
}

• recursion

var inorderTraversal = function(root) {
    let res = [];
    let dfs = (root) =>{
        if (root == null)return;
        dfs(root.left);
        res.push(root.val);
        dfs(root.right);
    }
    dfs(root);
    return res;
};