[HackerRank] Japan Population / Weather Observation Station 2 / Weather Observation Station 18

1) Japan Population

---

 

1. 문제

 

Query the sum of the populations for all Japanese cities in CITY. The COUNTRYCODE for Japan is JPN.

Input Format

 

The CITY table is described as follows: 

---

2. 답

SELECT SUM(population)
FROM city
WHERE countrycode = "JPN"

---

3. KEY POINT

 

• SUM(컬럼명) : 해당 컬럼의 합

---

 

 

www.hackerrank.com/challenges/japan-population/problem?h_r=internal-search

Japan Population | HackerRank

---

 

2) Weather Observation Station 2

---

1. 문제

 

Query the following two values from the STATION table:

1. The sum of all values in LAT_N rounded to a scale of 2 decimal places.
2. The sum of all values in LONG_W rounded to a scale of 2 decimal places.

Input Format

The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

 

Output Format

Your results must be in the form:

lat lon

 

where  lat is the sum of all values in LAT_N and lon is the sum of all values in LONG_W. Both results must be rounded to a scale of 2 decimal places.

---

2. 답

SELECT ROUND(SUM(lat_n), 2) AS lat, ROUND(SUM(long_w), 2) AS lon
FROM station

---

3. KEY POINT

 

• ROUND(컬럼명/값, n) : 값을 소수점 이하 n자릿수로 반올림
• AS : 별명 붙이기

---

 

www.hackerrank.com/challenges/weather-observation-station-2/problem?h_r=internal-search

Weather Observation Station 2 | HackerRank

---

 

3) Weather Observation Station 18

---

1. 문제

 

Consider P1(a,b) and P2(c,d) to be two points on a 2D plane.

• a happens to equal the minimum value in Northern Latitude (LAT_N in STATION).
• b happens to equal the minimum value in Western Longitude (LONG_W in STATION).
• c happens to equal the maximum value in Northern Latitude (LAT_N in STATION).
• d happens to equal the maximum value in Western Longitude (LONG_W in STATION).

Query the Manhattan Distance between points P1 and P2 and round it to a scale of 4 decimal places.

 

Input Format

 

The STATION table is described as follows:

where LAT_N is the northern latitude and LONG_W is the western longitude.

 

[ 참고 : Manhattan distance ]

정의:  The distance between two points measured along axes at right angles. In a plane with p1 at (x1, y1)

        and p2 at (x2, y2), it is |x1 - x2| + |y1 - y2|.

---

2. 답

SELECT ROUND(ABS(MIN(lat_n) - MAX(lat_n)) + ABS(MIN(long_w) - MAX(long_w)) , 4)
FROM station

---

3. KEY POINT

 

• ROUND(컬럼명/값, n) : 값을 소수점 이하 n자릿수로 반올림
• ABS(컬럼명/값) : 값의 절댓값을 반환
• MAX(컬럼명), MIN(컬럼명) : 해당 컬럼에서의 최댓값과 최솟값

---

 

www.hackerrank.com/challenges/weather-observation-station-18/problem?h_r=internal-search

Weather Observation Station 18 | HackerRank