[백준] 직사각형을 만드는 방법 8320번 (PYTHON,JAVA)

✔ 문제 8320 직사각형을 만드는 방법

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8320번: 직사각형을 만드는 방법

핵심 아이디어

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PYTHON

# 방법1. 가로 세로 탐색
N = int(input())

ans = 0
for i in range(1, N + 1):
    for j in range(i, N + 1):
        if i*j <= N:
            ans += 1
print(ans)

# 방법2. 규칙
N = int(input())

ans = N
for i in range(2, N):
    n = N // i - (i-1)
    if n < 1:
        break
    ans += n
print(ans)

JAVA

import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(br.readLine());
        int ans = 0;
        for (int i = 1; i <= N; i++){
            for (int j = i; j<=N; j++) {
                if (i*j <= N) ans += 1;
            }
        }
        System.out.println(ans);
    }
}

import java.util.*;
import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(br.readLine());
        int ans = N;
        for (int i = 2; i < N; i++){
            int tmp = N / i ;
            int n = tmp - (i-1);
            if(n < 1) break;
            ans += n;
        }
        System.out.println(ans);
    }
}