[HackerRank MySQL] Type of Triangle

Type of Triangle

Write a query identifying the type of each record in the TRIANGLES table using its three side lengths. Output one of the following statements for each record in the table:

• Equilateral: It's a triangle with 3 sides of equal length.
• Isosceles: It's a triangle with 2 sides of equal length.
• Scalene: It's a triangle with 3 sides of differing lengths.
• Not A Triangle: The given values of A, B, and C don't form a triangle.

Input Format

The TRIANGLES table is described as follows:

Each row in the table denotes the lengths of each of a triangle's three sides.

 

Sample Input

Sample Output

Isosceles
Equilateral
Scalene
Not A Triangle

 

Explanation

Values in the tuple (20, 20, 23) form an Isosceles triangle, because A ≠ B. 
Values in the tuple (20, 20, 20) form an Equilateral triangle, because A = B = C.

Values in the tuple (20, 21, 22) form a Scalene triangle, because A ≠ B ≠ C. 
Values in the tuple (13, 14, 30) cannot form a triangle because the combined value of sides A and B is not larger than that of side C.

select case when a+b>c and a+c>b and b+c>a then
        case when a=b and b=c then 'Equilateral'
             when a=b or a=c or b=c then 'Isosceles'
             else 'Scalene' end
        else 'Not A Triangle' end
from triangles

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Reference: HackerRank Practice > SQL > Advanced Select > Type of Triangle