52. Constexpr ADC Temperature Table

A temperature sensor in an embedded system produces ADC result indices that correspond to fixed, known temperature values.

To avoid runtime computation, the firmware must store these values in a compile-time lookup table using constexpr.

Your task is to define such a lookup table and use it to convert an ADC index into the corresponding temperature.

What you must do:

• Create a constexpr array named TEMP_TABLE
• The table must contain exactly 6 entries, mapped as follows:

• ADC Index	Temperature (°C)
  0	-40
  1	-10
  2	20
  3	50
  4	80
  5	120

• You must declare this table yourself using constexpr

Program input:

• Read an integer idx (range 0–5) representing the ADC result index

Program output:

• Print the corresponding temperature value from the lookup table
• No extra text

Example 1

Input:

3

Output:

50

Example 2 

Input:

0

Output:

-40 

Constraints:

• The lookup table must be defined using constexpr
• Runtime code must only read from the table — no computation allowed
• Input is guaranteed to be within 0–5
• Output must match exactly