백준 6단계 (함수)

15596번

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

 

 

4673번

import java.io.*;
import java.util.*;
 
public class Main {
    public static void main(String[] args) throws IOException {
 
        StringBuilder sb = new StringBuilder();
        
        boolean check[] = new boolean[10001];
        
        for(int i = 1; i < 10000; i++) {
            int n = d(i);
            
            if(n < 10001) {
                check[n] = true;
            }
        }
        
        for(int i = 1; i < check.length; i++) {
            if(!check[i]) {
                sb.append(i + "\n");
            }
        }
        
        System.out.println(sb);
    }
    
    
    public static int d(int num) {
        int sum = num;
        
        while(num != 0) {
            sum += num % 10;
            num = num / 10;
        }
        
        return sum;
        
    }
    
}

 

 

1065번

import java.io.*;
import java.util.*;
 
public class Main {
    public static void main(String[] args) throws IOException {
        
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        
        int cnt = 0;
        int N = Integer.parseInt(br.readLine());
        
        if(N < 100) {
            System.out.println(N);
        }
        else{
            cnt = 99;
            
            for(int i = 100; i <= N; i++) {
                cnt += d(i);
            }
            if(N == 1000)
                cnt--;
            
            System.out.println(cnt);
        }
            
    }
    
    
    public static int d(int num) {
        int A = num / 100 % 10;
        int B = num / 10 % 10;
        int C = num % 10;
        
        if(B * 2 == A + C) {
            return 1;
        }
        return 0;
    }
    
}