Count of Matches in Tournament — LeetCode 1688 Python Solution

The problem

You are given an integer n, the number of teams in a tournament that has strange rules: If the current number of teams is even, each team gets paired with another team. A total of n / 2 matches are played, and n / 2 teams advance to the next round.

Example

Input

n = 7

Output

6

Explanation

Details of the tournament:

Python solution

class Solution:
    def numberOfMatches(self, n: int) -> int:
        return n - 1

Complexity

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 1688. Count of Matches in Tournament is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Math.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

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