README.md

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.

Example 1:

Input: n = 7
Output: 6
Explanation: Details of the tournament:
- 1st Round: Teams = 7, Matches = 3, and 4 teams advance.
- 2nd Round: Teams = 4, Matches = 2, and 2 teams advance.
- 3rd Round: Teams = 2, Matches = 1, and 1 team is declared the winner.
Total number of matches = 3 + 2 + 1 = 6.

Example 2:

Input: n = 14
Output: 13
Explanation: Details of the tournament:
- 1st Round: Teams = 14, Matches = 7, and 7 teams advance.
- 2nd Round: Teams = 7, Matches = 3, and 4 teams advance.
- 3rd Round: Teams = 4, Matches = 2, and 2 teams advance.
- 4th Round: Teams = 2, Matches = 1, and 1 team is declared the winner.
Total number of matches = 7 + 3 + 2 + 1 = 13.

Constraints:

• 1 <= n <= 200

Solutions (Ruby)

1. Simulation

# @param {Integer} n
# @return {Integer}
def number_of_matches(n)
  if n == 1
    0
  elsif n.even?
    n / 2 + number_of_matches(n / 2)
  else
    (n - 1) / 2 + number_of_matches((n - 1) / 2 + 1)
  end
end

Solutions (Rust)

1. Simulation

impl Solution {
    pub fn number_of_matches(n: i32) -> i32 {
        if n == 1 {
            0
        } else if n % 2 == 0 {
            n / 2 + Self::number_of_matches(n / 2)
        } else {
            (n - 1) / 2 + Self::number_of_matches((n - 1) / 2 + 1)
        }
    }
}