Leetcode 1688 - Count of Matches in Tournament

Note:

  • Easy simulation.

Question:

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
2
3
4
5
6
7
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.

Code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
/**
* @param {number} n
* @return {number}
*/
var numberOfMatches = function(n) {
let ans = 0;
while (n > 1) {
if (n % 2 === 0) {
ans += n / 2;
n = n / 2;
} else {
ans += (n - 1) / 2;
n = 1 + (n - 1) / 2;
}
}
return ans;
};