Question

题目内容

解题思路

递归​。

代码实现

/**
 * 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)
 *     }
 * }
 */

const diameterOfBinaryTree = (root: TreeNode | null): number => {
  let ans: number = 0;
  const depth = (rootNode: TreeNode | null): number => {
    if (!rootNode) return 0;
    const L: number = depth(rootNode.left);
    const R: number = depth(rootNode.right);
    ans = Math.max(ans, L + R + 1); // 将每个节点最大直径（左子树深度 + 右子树深度) 与当前最大值比较并取大者
    return Math.max(L, R); // 返回节点深度
  };
  depth(root);
  return ans;
};