## 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 = 7Output:6Explanation: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 = 14Output:13Explanation: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`

## Rust Solution

```
struct Solution;
impl Solution {
fn number_of_matches(mut n: i32) -> i32 {
let mut res = 0;
while n > 1 {
if n % 2 == 1 {
res += 1;
}
n /= 2;
res += n;
}
res
}
}
#[test]
fn test() {
let n = 7;
let res = 6;
assert_eq!(Solution::number_of_matches(n), res);
let n = 14;
let res = 13;
assert_eq!(Solution::number_of_matches(n), res);
}
```

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