第五章 大数定律和中心极限定理
（1）切比雪夫不等式
$X$有数学期望$E(X)=\mu,D(X=\sigma^2)$, 则对任意正整数$\varepsilon$
$P{\left| x - \mu \right| \geq \varepsilon } \leq \frac{\sigma ^2}{\varepsilon ^ 2}$
$P\{\left| x - \mu \right| < \varepsilon \} \geq 1-\frac{\sigma ^2}{\varepsilon ^ 2}$
第四章 随机变量的数字特征
离散型
$$
E(X)=\sum_{k=1}^{\infty} x_{k} p_{k}
$$
当上式发散时，$X$的数学期望不存在。
Let's stimulate the situation by ourselves first.
Using C++ Sort.
Turn then into positive numbers and sort. And for each unit in array, if it’s negative originally, turn it back to negative.
As you can easily see, for each point tower[i][j] , it has two parent points, warning...
No tricks but you need to be very careful or you will not be able to make it.
Using C++ 11 features. reverse. Another way is is find the middle of the string and travers from both side. Compare one by one.
As you can see from the picture, for each unit, there is...
Just stimulate the rule of clock time addition.