LEETCODE
===
# 1802. Maximum Value at a Given Index in a Bounded Array
看不出來解答為什麼這麼寫

func maxValue(n int, index int, maxSum int) int {
    return sort.Search(maxSum, func(t int) bool {
        s := t*t
        if a := t - index; a > 1 {
            s -= (a - 1) * a / 2
        }
        if b := t - (n - 1 - index); b > 1 {
            s -= (b - 1) * b / 2
        }
        return s > maxSum - n
    })

先用 [this](https://leetcode.com/problems/maximum-value-at-a-given-index-in-a-bounded-array/editorial/?envType=daily-question&envId=2023-11-06) 做一次吧

## 543. Diameter of Binary Tree
找的是距離，不是高度