544. Output Contest Matches

Problem Link : https://leetcode.com/problems/output-contest-matches/
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Complexity : Time-O(N*log(N)*stringconcatenationTime), Memory-O(N), TimeTaken-<1hr
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Logic :
Hint here is to always match the player at index 1 with index n
With the help of this we always match player with index 1 with n, i+1 with n-1 and so on
and we repeat this process till we have only one element in list
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class Solution {
    public String findContestMatch(int n) {
        int rounds=(int)(Math.log(n)/Math.log(2));
        List<String> teams=new ArrayList();
        for(int i=1;i<=n;i++){
            teams.add(i+"");
        }
        while(rounds>0){
            int s=0, e=teams.size()-1;
            List<String> round=new ArrayList();
            while(s<e){
                round.add("("+teams.get(s++)+","+teams.get(e--)+")");
            }
            teams=round;
            --rounds;   
        }
        return teams.get(0);
    }
}