알고리즘입문(Java) - [효율성 : O(n^2)-->O(n)] 5.연속된 자연수의 합

 

 

 

 

 

(풀이)

import java.util.*;
class Main {
    public int solution(int n){
        int answer=0, sum=0;
        int m=n/2+1;
        int[] arr=new int[m];
        for(int i=0; i<m; i++) arr[i]=i+1;

        for(int rt=0; rt<m; rt++){
            sum+=arr[rt];
            if(sum==n) answer++;
            while(sum>=n){
                sum-=arr[lt++];
                if(sum==n) answer++;
            }
        }
        return answer;
    }

    public static void main(String[] args){
        Main T = new Main();
        Scanner kb = new Scanner(System.in);
        int n=kb.nextInt();
        System.out.print(T.solution(n));
    }
}

 

 

(풀이 2)

import java.util.*;
class Main {
    public int solution(int n){
        int answer=0, cnt=1;
        n--;
        while(n>0){
            cnt++;
            n=n-cnt;
            if(n%cnt==0) answer++;
        }
        return answer;
    }

    public static void main(String[] args){
        Main T = new Main();
        Scanner kb = new Scanner(System.in);
        int n=kb.nextInt();
        System.out.print(T.solution(n));
    }
}