백준17298

이중 반복문

import java.util.Arrays;

public class Baek17298 {
    public static void main(String[] args) {
        int[] input = {3,5,2,7};
        int[] result = new int[4];
        Arrays.fill(result,-1);

        for(int i=0;i<4;i++){
            for(int j=i+1;j<4;j++){
                if(input[i]<input[j]){
                    result[i]=input[j];
                    break;
                }
            }
        }
        for(int k : result) System.out.println(k);
    }
}

스택이용

import java.io.IOException;
import java.util.Arrays;
import java.util.Scanner;
import java.util.Stack;
import java.util.StringTokenizer;


public class Baek17298 {

    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.nextLine());
        int[] answer = new int[N];
        Arrays.fill(answer, -1);
        StringTokenizer st = new StringTokenizer(sc.nextLine());
        Stack<int[]> stack = new Stack<>();
        for(int i=0;i<N;i++) {
            int val=Integer.parseInt(st.nextToken());
            if(stack.size()==0) stack.push(new int[] {val,i});
            else {
                if(stack.peek()[0]>val) stack.push(new int[] {val,i});
                else {
                    while(stack.size()>0&&stack.peek()[0]<val) answer[stack.pop()[1]]=val;
                    stack.push(new int[] {val,i});
                }
            }
        }
        for(int i=0;i<N;i++) System.out.print(answer[i]+" ");
    }
}