2225. Find Players With Zero or One Losses

Medium
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.

解題

func findWinners(matches [][]int) [][]int {
m := make(map[int]int)
v := make(map[int]bool)
​
for _, match := range matches {
m[match[1]]++
v[match[1]] = true
v[match[0]] = true
}
​
res := [][]int{}
res = append(res, []int{})
res = append(res, []int{})
​
for k := range v {
if m[k] == 0 {
res[0] = append(res[0], k)
} else if m[k] == 1 {
res[1] = append(res[1], k)
}
}
​
sort.Ints(res[0])
sort.Ints(res[1])
​
return res
}