算法第五天-01的概率问题+mysql复习

01由不等概率转变为等概率：

packageRandom.随机函数;/**
 * 不等概率的01----->等概率01
 */publicclassTest2{publicstaticintx(){returnMath.random()<0.84?0:1;}/**
     * 等概率的01   先判断一次，ans要是是0，在判断一次，要是还是0，返回0，要是1就重来一次，同理1也这样，01就是等概率
     * @return
     */publicstaticinty(){int ans =0;do{
            ans =x();}while(ans==x());return  ans;}}

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MYSQL

这个题是三个表，我们的思维就是化成两个表，将其中两个表通过内连接合并，然后再和第一个表左连接查询

SELECT e.last_name, e.first_name, b.dept_name
FROM employees AS e
LEFTJOIN(SELECT d.dept_no,d.dept_name,de.emp_no
FROM departments AS d
INNERJOIN dept_emp AS de
ON d.dept_no=de.dept_no
)AS b
ON e.emp_no=b.emp_no;