Tournament Winners - Leetcode Solution

Problem Statement:

You are given a list of matches in a tournament, where each element in the list represents a match that was played in the tournament. The matches are represented by an array of two strings: [homeTeam, awayTeam], where homeTeam is the name of the home team and awayTeam is the name of the away team.

Each match has a winner, which is represented by a string. If the home team won the match, winner = homeTeam. If the away team won the match, winner = awayTeam. If the match ended in a draw, winner = "Draw".

Return a list of the names of the teams that won the tournament. The list should be in descending order based on the number of wins of each team. If two or more teams have the same number of wins, arrange them in alphabetical order.

Example:

Input: matches = [["Team1","Team2"],["Team2","Team3"],["Team3","Team1"]] Output: ["Team1","Team2","Team3"] Explanation: Team1 won 1 match, Team2 won 1 match, and Team3 won 1 match. Therefore, they all won the tournament.

Input: matches = [["Team1","Team2"],["Team2","Team3"],["Team3","Team1"],["Team1","Team2"],["Team2","Team3"],["Team3","Team1"],["Team1","Team2"],["Team2","Team3"],["Team3","Team1"]] Output: ["Team1","Team2","Team3"] Explanation: After playing all the matches, each team won 3 matches. Therefore, they all won the tournament.

Solution:

The approach to solve this problem is to count the number of wins for each team. We can create a hashmap where the key is the team name, and the value is the number of wins for that team. We can loop through each match and update the count of the winning team in the hashmap. Finally, we can return a list of teams sorted by the number of wins and then by alphabetical order.

Algorithm:

1. Initialize a hashmap called "wins" to store the number of wins for each team.
2. Loop through each match in the input list "matches". a. Get the home team and away team from the current match. b. If the winner of the match is the home team, increment the number of wins for the home team in the "wins" hashmap, or if the winner of the match is the away team, increment the number of wins for the away team in the "wins" hashmap.
3. Initialize a list called "result" to store the names of teams that won the tournament.
4. Sort the keys of "wins" based on the number of wins in descending order and then by alphabetical order if the number of wins is equal, and append the teams to "result".
5. Return "result".

Code:

def tournamentWinners(matches): wins = {} for match in matches: home_team, away_team = match winner = home_team if home_team != 'Draw' else away_team wins[winner] = wins.get(winner, 0) + 1

result = sorted(wins.keys(), key=lambda x: (-wins[x], x))

return result

Time Complexity: O(NlogN), where N is the number of matches in the tournament. We need to sort the teams based on their number of wins, which takes O(NlogN) time.

Space Complexity: O(N), where N is the number of matches in the tournament. We need to store the number of wins for each team in the hashmap.

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