pub struct Solution;
剑指 Offer 47. 礼物的最大价值 https://leetcode.cn/problems/li-wu-de-zui-da-jie-zhi-lcof/
TypeId
self
Returns the argument unchanged.
Calls U::from(self).
U::from(self)
That is, this conversion is whatever the implementation of From<T> for U chooses to do.
From<T> for U