Leetcode: Triangle Judgement

Triangle Judgement

Similar Problems:

• CheatSheet: SQL & MySql
• CheatSheet: Leetcode For Code Interview
• Tag: #sql, #triangle

A pupil Tim gets homework to identify whether three line segments could possibly form a triangle.
However, this assignment is very heavy because there are hundreds of records to calculate.
Could you help Tim by writing a query to judge whether these three sides can form a triangle, assuming table triangle holds the length of the three sides x, y and z.

| x  | y  | z  |
|----|----|----|
| 13 | 15 | 30 |
| 10 | 20 | 15 |

For the sample data above, your query should return the follow result:

| x  | y  | z  | triangle |
|----|----|----|----------|
| 13 | 15 | 30 | No       |
| 10 | 20 | 15 | Yes      |

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

## Blog link: https://code.dennyzhang.com/triangle-judgement
select x, y, z,
       case
           when x+y>z and y+z>x and x+z>y then 'Yes'
           else 'No'
       end as triangle
from triangle

## Basic Ideas: max(x, y, z) < sum(x, y, z)/2
# select x, y, z, if(max_value<sum_value/2, 'Yes', 'No') as triangle
# from (
#     select *, x+y+z as sum_value,
#         case
#             when x>=y and x>=z then x
#             when y>=x and y>=z then y
#             when z>=x and z>=y then z
#             else x
#         end as max_value
#     from triangle) as t