[백준] 6단계 문제 모음

1

15596

정수 N개의 합

public class Test {
    long sum(int[] a) {
        long ans = 0;
        for(int i=0; i<a.length; i++){
            ans += a[i];
        }
        return ans;
    }
}

---

2

4673

셀프 넘버

    class lol{
        lol(){
            int a = 1;
        System.out.println(a);
        for(int n=2; n<10001; n++){
            for(int j=1; j<n; j++){
                if(0<j && j < 100){
                    if(n == j + (j/10) + (j%10)) break;
                    if(j == n-1) System.out.println(n);
                }
                if(100<j && 1000>j){
                    if(n== j + (j/100) + ((j%100)/10) + (j%10)) break;
                    if(j == n-1) System.out.println(n);
                }
                if(1000<j && j<10000){
                    if(n== j + (j/1000) + ((j%1000)/100) + ((j%100)/10) + j%10) break;
                    if(j == n-1) System.out.println(n);
                }
        
            }
        }
        }
    }    


public class Main{

     public static void main(String []args){
        new lol();
     }
     
}

---

3

1065

한수

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		scan.close();
		int count =0;
		
		if(n<100) { //n이 100이 안되면.
			for(int i = 0; i<n; i++) count++;
			System.out.println(count);
		}
		if(n>=100 && n<1000) {	//n이 3자리수 이면.
			count = 99; //1~100까지의 한수 미리 저장.

			for(int i=100; i<=n; i++) {
				int x = i;
				int a = x/100;
				int b = x/10 - a*10;
				int c = x%10;
				
				if(a==b && b==c) {
					count++;
					continue;
					}
				if(a+1 == b && b+1 ==c) {
					count++;
					continue;
				}
				if(a+2 == b && b+2 ==c) {
					count++;
					continue;
				}
				if(a+3 == b && b+3 ==c) {
					count++;
					continue;
				}
				if(a+4 == b && b+4 ==c) {
					count++;
					continue;
				}
				if(c+1 == b && b + 1 == a) {
					count++;
					continue;
				}
				if(c+2 == b && b + 2 == a) {
					count++;
					continue;
				}
				if(c+3 == b && b + 3 == a) {
					count++;
					continue;
				}
				if(c+4 == b && b + 4 == a) {
					count++;
					continue;
				}
			}
				System.out.println(count);
		}
		if(n==1000)
			System.out.println(144);
	}

}