백준 17299번

package Baekjoon;
//https://www.acmicpc.net/problem/17299 문제
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Stack;
 
public class Number17299{
 
    public static void main(String[] args) throws IOException {
 
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
 
        int size = Integer.parseInt(br.readLine());  //첫줄을 int형으로 바꿔서 저장
        
        String[] temp = br.readLine().split(" ");
        // 다음 라인 받아서 공백을 기준으로 잘라서 임시로 string 배열에 담아줌
        int[] numbers = new int[size];
        // 크기 비교를 위해 int 배열로 변경
        int[] counts = new int[1000001];
        // 해당 숫자가 몇 번 나왔는지 기록해둘 배열 생성해서
        int[] answer = new int[size];
        // 오등 큰수 저장할 배열
 
        for (int i = 0; i < size; i++) {
            numbers[i] = Integer.parseInt(temp[i]);
            // 임시변수에 저장해두었던 배열을 int형으로 바꿔서 저장
            counts[numbers[i]] += 1;
            //해당 숫자가 몇번 나왔는지를 알기 위해서 숫자가 나온만큼 count를 해줌
        }
 
        Stack<Integer> stack = new Stack<Integer>();
 
        stack.push(0);
        // 처음 인덱스는 그냥 넣고
        for (int i = 1; i < size; i++) { //0번째 자리와 1번째 자리와 비교하므로
            // 1부터 끝까지 반복
            if (stack.isEmpty()) {
                // 스택이 비어있는 경우에는
                stack.push(i);
                // 그냥 스택에 인덱스 저장
            }
            
            while (!stack.isEmpty() && counts[numbers[stack.peek()]] < counts[numbers[i]]) {
                // 스택이 비어있지 않고 숫자가 스택 가장 윗 숫자와 비교해서 큰 경우 반복
                answer[stack.pop()] = numbers[i];
                // stack 하나 비우면서 그 인덱스에 숫자를 넣는다
            }
            stack.push(i);
            // 반복이 끝나면 다음에 비교할 값 stack에 입력
 
        }
 
        while (!stack.isEmpty()) {
            // 반복문이 모두 끝난 후에도 stack에 값이 있다면
            answer[stack.pop()] = -1;
            // 빌때까지 해당 인덱스에 -1을 넣는다
        }
 
        for (int i = 0; i < size; i++) {
            bw.write(String.valueOf(answer[i] + " ")); //배열안에 들어 있는 수를 string으로 변환시켜서 출력
            // 출력
        }
        bw.write("\n");
        bw.flush();
        
        bw.close();
        br.close();
    }
 
}