LeetCode-in-Java
1688. Count of Matches in Tournament
Easy
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 / 2matches are played, andn / 2teams 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) / 2matches are played, and(n - 1) / 2 + 1teams 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
Solution
public class Solution {
public int numberOfMatches(int n) {
int matches = 0;
while (n > 1) {
if (n % 2 == 0) {
matches += n / 2;
n /= 2;
} else {
matches += (n - 1) / 2;
n = (n + 1) / 2;
}
}
return matches;
}
}