2022-10-21

[Zheaoli]

2022-10-21

[Dapeus]

[gongpeione]

/*
 * @lc app=leetcode id=145 lang=typescript
 *
 * [145] Binary Tree Postorder Traversal
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */
function postorderTraversal(root: TreeNode | null): number[] {
    const ans = [];

    const walk = (node) => {
        node?.left && walk(node.left);
        node?.right && walk(node.right);

        node?.val && ans.push(node.val);
    }

    walk(root);

    return ans;
};
// @lc code=end

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