1688. Count of Matches in Tournament

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.
• If the current number of teams is odd, one team randomly advances in the tournament, and the rest gets paired. A total of (n - 1) / 2 matches are played, and (n - 1) / 2 + 1 teams advance to the next round.

Return the number of matches played in the tournament until a winner is decided.

class Solution {
public:
    int numberOfMatches(int n) {
        int res = 0;
        while(n > 1) {
            res += n / 2;
            n = (n + 1) / 2;
        }
        return res;
    }
};