2225. Find Players With Zero or One Losses

2225. Find Players With Zero or One Losses

Medium

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You are given an integer array matches where matches[i] = [winneri, loseri] indicates that the player winneri defeated player loseri in a match.

Return a list answer of size 2 where:

• answer[0] is a list of all players that have not lost any matches.
• answer[1] is a list of all players that have lost exactly one match.

The values in the two lists should be returned in increasing order.

Note:

• You should only consider the players that have played at least one match.
• The testcases will be generated such that no two matches will have the same outcome.

 

Example 1:

Input: matches = [[1,3],[2,3],[3,6],[5,6],[5,7],[4,5],[4,8],[4,9],[10,4],[10,9]]
Output: [[1,2,10],[4,5,7,8]]
Explanation:
Players 1, 2, and 10 have not lost any matches.
Players 4, 5, 7, and 8 each have lost one match.
Players 3, 6, and 9 each have lost two matches.
Thus, answer[0] = [1,2,10] and answer[1] = [4,5,7,8].

 

Constraints:

• 1 <= matches.length <= 105
• matches[i].length == 2
• 1 <= winneri, loseri <= 105
• winneri != loseri
• All matches[i] are unique.

이 문제는 한번도 진적이 없는 사람들과 딱 한 번만 진 사람들을 찾는 문제입니다.

map을 이용해서 간단하게 풀수 있습니다.

처음에는 winner, loser 둘 다 따로 map을 만들어서 풀었지만

그것보다 둘이 합쳐서 관리하는 게 더 좋다고 생각해서 리팩터링 한 문제입니다.

조건에 맞는 사람들을 찾기 위해 이긴사람은 값을 0 

진 사람은 계속해서 1을 더한값을 저장해주었습니다. 

 

/**
 * @param {number[][]} matches
 * @return {number[][]}
 */
var findWinners = function(matches) {
    const total = new Map()
    
    for(const match of matches){
        const [win, lose] = match
        
        total.set(win, (total.get(win)||0))
        total.set(lose, (total.get(lose)||0)+1)
    }
    
    const winner = [] , loser = []
    
    for(const [key, value] of total){
        if(value === 0) winner.push(key)
        if(value === 1) loser.push(key)
    }
    
    winner.sort((a,b)=>a-b)
    loser.sort((a,b)=>a-b)
    
    return [winner, loser]
};