level - easy
[문제 내용]
제목 그대로 원형 트랙에서 가장 많이 방문하는 트랙을 반환
[example 1]
Input: n = 4, rounds = [1,3,1,2]
Output: [1,2]
Explanation: The marathon starts at sector 1. The order of the visited sectors is as follows:
1 --> 2 --> 3 (end of round 1) --> 4 --> 1 (end of round 2) --> 2 (end of round 3 and the marathon)
We can see that both sectors 1 and 2 are visited twice and they are the most visited sectors. Sectors 3 and 4 are visited only once.[example 2]
Input: n = 2, rounds = [2,1,2,1,2,1,2,1,2]
Output: [2][example 3]
Input: n = 7, rounds = [1,3,5,7]
Output: [1,2,3,4,5,6,7][해결 방법]
round 순서대로 방문 개수를 count하는 가장 간단한 방식으로 풀었다.
class Solution {
public List<Integer> mostVisited(int n, int[] rounds) {
final HashMap<Integer, Integer> visited = new HashMap<>();
for(int i=1; i<=n; i++) {
visited.put(i, 0);
}
visited.put(rounds[0], visited.get(rounds[0]) + 1);
for(int i=0; i<rounds.length-1; i++) {
int start = rounds[i];
int end = rounds[i+1];
if(end <= n && start < end) {
for(int j=start+1; j<=end; j++) {
visited.put(j, visited.get(j)+1);
}
} else {
for(int j=start+1; j<=n; j++) {
visited.put(j, visited.get(j)+1);
}
for(int j=1; j<=end; j++) {
visited.put(j, visited.get(j)+1);
}
}
}
ArrayList<Integer> keySet = new ArrayList<>(visited.keySet());
Collections.sort(keySet, new Comparator<Integer>() {
@Override
public int compare(Integer integer, Integer t1) {
return visited.get(t1).compareTo(visited.get(integer));
}
});
ArrayList<Integer> maxList = new ArrayList<>();
int max = visited.get(keySet.get(0));
for(int key : keySet) {
if(max > visited.get(key)) {
break;
}
maxList.add(key);
}
Collections.sort(maxList);
return maxList;
}
}