aeightchill

[백준] 27961. 고양이는 많을수록 좋다 / 브론즈1코드 변수 정의cnt : 연산 횟수madoka_cat : 현재 고양이 수Greedy시간복잡도 : O(logN)def f(): N = int(input()) cnt, madoka_cat = 0, 0 # 연산 횟수(cnt)와 현재 고양이 수(madoka_cat) 초기화 while madoka_cat    풀이 방식 고양이 수를 증가시키는 과정에서 최소한의 연산 횟수를 찾는 문제로, 고양이 수 madoka_cat은 두 가지 방법으로 증가할 수 있다.생성 마법    →     +1 연산복제 마법    →     x2 연산마도카의 집에 있는 고양이 일부 또는 전부를 대상으로 하여 복제한다.0마리 이상 k마리 이하의 고양이를 추가할 수 있으므로..

[SQL50] 1934. Confirmation Rate (JOIN)WITH all_action AS( SELECT user_id, SUM(1) AS action_cnt FROM Confirmations GROUP BY user_id),confirmed AS( SELECT user_id, SUM(1) AS confirmed_cnt FROM Confirmations WHERE action = 'confirmed' GROUP BY user_id),divide AS( SELECT A.user_id, ROUND(B.confirmed_cnt / A.action_cnt ::decimal, 2) AS confirmation_rate FROM all_action A LE..

[SQL50] 570. Managers with at Least 5 Direct Reports (JOIN)WITH direct AS( SELECT managerId, SUM(1) AS manage_cnt FROM Employee WHERE managerId IS NOT NULL GROUP BY managerId)SELECT A.nameFROM Employee A LEFT JOIN direct B ON A.id = B.managerIDWHERE B.manage_cnt >= 5;

[SQL50] 1280. Students and Examinations (JOIN)WITH attend_class AS( SELECT student_id, subject_name, SUM(1) AS attended_exams FROM Examinations GROUP BY student_id, subject_name)SELECT A.student_id, A.student_name, A.subject_name, CASE WHEN C.attended_exams IS NULL THEN 0 ELSE C.attended_exams END AS attended_examsFROM (Students CROSS JOIN Subjects) AS A LEFT JOIN attend_class C ON A.st..

[SQL50] 577. Employee Bonus (JOIN) SELECT A.name, B.bonusFROM Employee A LEFT JOIN Bonus B ON A.empId = B.empIdWHERE bonus

[SQL50] 1661. Average Time of Process per Machine (JOIN)WITH take_time AS( SELECT machine_id, process_id, SUM(CASE WHEN activity_type = 'start' THEN -1 * timestamp ELSE timestamp END) FROM Activity GROUP BY machine_id, process_id)SELECT machine_id, ROUND(AVG(sum) ::decimal, 3) AS processing_timeFROM take_timeGROUP BY machine_id;WITH ~ AS( ... )WITH AS로 임시 테이블 생성하여 활용https://youngone-kan..

[SQL50] 197. Rising Temperature (JOIN)SELECT A.idFROM Weather A LEFT JOIN (SELECT id, LAG(recordDate, 1) OVER(ORDER BY recordDate) AS yesterday, LAG(temperature, 1) OVER(ORDER BY recordDate) AS prev_temp FROM Weather) B ON A.id = B.idWHERE temperature > B.prev_temp AND B.yesterday = recordDate - 1;LAG이전 행의 값을 가져올 수 있다. SELECT t, val, LAG(val) AS 'lag'FROM seriesO..

[SQL50] 1581. Customer Who Visited but Did Not Make Any Transactions (JOIN)SELECT A.customer_id, SUM(1) AS count_no_transFROM Visits A LEFT JOIN Transactions B ON A.visit_id = B.visit_idWHERE transaction_id IS NULLGROUP BY customer_id;

[SQL50] 1068. Product Sales Analysis I (JOIN)SELECT B.product_name, A.year, A.priceFROM Sales A LEFT JOIN Product B ON A.product_id = B.product_id;

[SQL50] 1378. Replace Employee ID With The Unique Identifier (JOIN)SELECT B.unique_id, A.nameFROM Employees A LEFT JOIN EmployeeUNI B ON A.id = B.id;