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2225. Find Players With Zero or One Losses

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Description

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].

Example 2:

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

 

Constraints:

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

Solutions

Python3

class Solution:
    def findWinners(self, matches: List[List[int]]) -> List[List[int]]:
        cnt = Counter()
        for a, b in matches:
            if a not in cnt:
                cnt[a] = 0
            cnt[b] += 1
        ans = [[], []]
        for u, v in cnt.items():
            if v < 2:
                ans[v].append(u)
        ans[0].sort()
        ans[1].sort()
        return ans

Java

class Solution {
    public List<List<Integer>> findWinners(int[][] matches) {
        Map<Integer, Integer> cnt = new HashMap<>();
        for (int[] m : matches) {
            int a = m[0], b = m[1];
            cnt.putIfAbsent(a, 0);
            cnt.put(b, cnt.getOrDefault(b, 0) + 1);
        }
        List<List<Integer>> ans = new ArrayList<>();
        ans.add(new ArrayList<>());
        ans.add(new ArrayList<>());
        for (Map.Entry<Integer, Integer> entry : cnt.entrySet()) {
            int u = entry.getKey();
            int v = entry.getValue();
            if (v < 2) {
                ans.get(v).add(u);
            }
        }
        Collections.sort(ans.get(0));
        Collections.sort(ans.get(1));
        return ans;
    }
}

C++

class Solution {
public:
    vector<vector<int>> findWinners(vector<vector<int>>& matches) {
        unordered_map<int, int> cnt;
        for (auto& m : matches) {
            int a = m[0], b = m[1];
            if (!cnt.count(a)) cnt[a] = 0;
            ++cnt[b];
        }
        vector<vector<int>> ans(2);
        for (auto& [u, v] : cnt) {
            if (v < 2) ans[v].push_back(u);
        }
        sort(ans[0].begin(), ans[0].end());
        sort(ans[1].begin(), ans[1].end());
        return ans;
    }
};

Go

func findWinners(matches [][]int) [][]int {
	cnt := map[int]int{}
	for _, m := range matches {
		a, b := m[0], m[1]
		if _, ok := cnt[a]; !ok {
			cnt[a] = 0
		}
		cnt[b]++
	}
	ans := make([][]int, 2)
	for u, v := range cnt {
		if v < 2 {
			ans[v] = append(ans[v], u)
		}
	}
	sort.Ints(ans[0])
	sort.Ints(ans[1])
	return ans
}

TypeScript

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