pub struct Solution;
剑指 Offer 04. 二维数组中的查找 https://leetcode.cn/problems/er-wei-shu-zu-zhong-de-cha-zhao-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