Solutions to HackerRank practice problems 📝

💡Duration💡

- JAN 26, 2023 to current

🎯Language🎯

-

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< MySQL >

#	PROBLEM	SOLUTION	DIFFICULTY	SCORE	CHALLENGE WHY
1	Select All	Solution	Easy	10	---
2	Weather Observation Station 1	Solution	Easy	15	---
3	Revising the Select Query I	Solution	Easy	10	---
4	Select By ID	Solution	Easy	10	---
5	Weather Observation Station 6	Solution	Easy	10	---
6	Weather Observation Station 12	Solution	Easy	15	---
7	Employee Names	Solution	Easy	10	---
8	Employee Salaries	Solution	Easy	15	---
9	Higher Than 75 Marks	Solution	Easy	15	---
10	Weather Observation Station 15	Solution	Easy	15	LIMIT
11	Revising the Select Query II	Solution	Easy	10	---
12	Japanese Cities' Attributes	Solution	Easy	10	---
13	Japanese Cities' Names	Solution	Easy	10	---
14	Weather Observation Station 3	Solution	Easy	10	---
15	Weather Observation Station 4	Solution	Easy	10	---
16	Weather Observation Station 7	Solution	Easy	10	LIKE
17	Revising Aggregations - Averages	Solution	Easy	10	---
18	Revising Aggregations - The Sum Function	Solution	Easy	10	---
19	Average Population	Solution	Easy	10	---
20	Revising Aggregations - The Count Function	Solution	Easy	10	---
21	Population Density Difference	Solution	Easy	10	---
22	Top Earners	Solution	Easy	20	COUNT(*) : COUNT THE NUMBER OF ROW (GROUP BY)
23	Weather Observation Station 2	Solution	Easy	15	---
24	Weather Observation Station 13	Solution	Easy	10	---
25	Weather Observation Station 14	Solution	Easy	10	---
26	Weather Observation Station 8	Solution	Easy	15	---
27	Weather Observation Station 16	Solution	Easy	10	---
28	Weather Observation Station 17	Solution	Easy	15	WHERE MIN() > is not working, so I should write the query with ORDER BY & LIMIT to print out the min()
29	Japan Population	Solution	Easy	10	---
30	African Cities	Solution	Easy	10	---
31	Type of Triangle	Solution	Easy	20	runtime error: put wrong attribute(type) in SELECT
32	Average Population of Each Continent	Solution	Easy	10	GROUP BY
33	Weather Observation Station 5	Solution	Easy	30	ORDER BY : first column sorted first, and the next column will be sorted based on the first sort
34	Weather Observation Station 9	Solution	Easy	10	---
35	Weather Observation Station 10	Solution	Easy	10	---
36	Weather Observation Station 11	Solution	Easy	10	---
37	The Blunder	Solution	Easy	15	REPLACE **
38	Population Census	Solution	Easy	10	Key Column should be match!
39	Weather Observation Station 18	Solution	Medium	25	---
40	Weather Observation Station 19	Solution	Medium	30	SQRT : return the square root of a number , POWER
41	Symmetric Pairs	Solution	Medium	0	---
42	Placements	Solution	Medium	40	subquery in from and use alias for main query
43	The Report	Solution	Medium	0	---
44		Solution	Medium	0	---
45		Solution	Medium	0	---
46		Solution	Medium	0	---
47		Solution	Medium	0	---
48		Solution	Medium	0	---
49		Solution	Medium	0	---
50		Solution	Medium	0	---

< Python >

#	PROBLEM	SOLUTION	DIFFICULTY	SCORE	CHALLENGE WHY
1	Say "Hello, World!" With Python	Solution	Easy	5	---
2	Python If-Else	Solution	Easy	10	---
3	Loops	Solution	Easy	10	---
4	Python: Division	Solution	Easy	10	---
5	Arithmetic Operators	Solution	Easy	10	---
6	Print Function	Solution	Easy	20	end="" : print without newline
7	Mutations	Solution	Easy	10	---
8	Find a string	Solution	Easy	10	---
9	sWAP cASE	Solution	Easy	10	---
10		Solution	Easy	0	---
11		Solution	Easy	0	---
12		Solution	Easy	0	---
13		Solution	Easy	0	---
14		Solution	Medium	0	---
15		Solution	Medium	0	---
16		Solution	Medium	0	---
17		Solution	Easy	0	---
18		Solution	Easy	0	---
19		Solution	Easy	0	---
20		Solution	Easy	0	---
21		Solution	Easy	0	---
22		Solution	Easy	0	---
23		Solution	Easy	0	---
24		Solution	Medium	0	---
25		Solution	Medium	0	---
26		Solution	Medium	0	---
27		Solution	Easy	0	---
28		Solution	Easy	0	---
29		Solution	Easy	0	---
30		Solution	Easy	0	---