## Editorial for TLE '17 Contest 7 P1 - Stargazing

Remember to use this editorial

**only**when stuck, and**not to copy-paste code from it**. Please be respectful to the problem author and editorialist.**Submitting an official solution before solving the problem yourself is a bannable offence.**Author:

Use two arrays to keep track of the and coordinates for every planet. Let the first planet be located at the origin . For each other planet, calculate its and coordinates relative to the first planet, using the and coordinates of a previously located planet:

After that, there are two main ways to count the number of distinct pairs of coordinates:

Insert all the pairs of coordinates into a set. The size of the set will be your answer.

**Time Complexity:**For each planet, loop through all previous planets to check if their coordinates match. If that new planet is unique so far, increment your answer by one.

**Time Complexity:**

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