백준 8단계 (기본 수학1)

1712번

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)); 
        
        StringTokenizer st;
        
        st = new StringTokenizer(br.readLine()," ");
        
        int A = Integer.parseInt(st.nextToken());
        int B = Integer.parseInt(st.nextToken());
        int C = Integer.parseInt(st.nextToken());
        
        if(C <= B)
            System.out.println("-1");
        else
            System.out.println((A / (C - B)) + 1);
    }
}

 

 

2292번

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 N = Integer.parseInt(br.readLine());
        
        // 최소 개수
        int  cnt = 1;
        
        while(true) {
            int num = cnt - 1;
            // 범위의 끝 값(1, 7, 19, 37, 61......)
            int temp = 6 * (num * (num + 1) / 2) + 1;
            
            if(N <= temp) {
                System.out.println(cnt);
                break;
            }
            cnt++;
        }
            
    }
}

 

 

1193번

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
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 line = 0;
        int num = 0;
        
        // 몇 번째 대각선인지 찾기
        for(int i = 0; i <= N; i++) {
            num += i;
            if(num >= N) {
                line = i;
                break;
            }
        }
        
        if(line % 2 == 0)
            System.out.println(line - (num - N) + "/" + (1 + num - N));
        else
            System.out.println((1 + num - N) + "/" + (line - (num - N)));
        
    }
}

 

 

2869번

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)); 
        
        StringTokenizer st;
        
        st = new StringTokenizer(br.readLine()," ");
        
        // 낮에 올라가는 높이
        int A = Integer.parseInt(st.nextToken());
        // 밤에 떨어지는 높이
        int B = Integer.parseInt(st.nextToken());
        // 나무 높이
        int V = Integer.parseInt(st.nextToken());
        
        
        int day = (V - B) / (A - B);
        
        if((V - B) % (A - B) != 0)
            day++;
        
        System.out.println(day);
        
        
    }
}

 

 

10250번

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)); 
        StringBuilder sb = new StringBuilder();
        StringTokenizer st;
        
        int num = Integer.parseInt(br.readLine());
        
        for(int i = 0; i < num; i++) {
            st = new StringTokenizer(br.readLine()," ");
            int H = Integer.parseInt(st.nextToken());
            int W = Integer.parseInt(st.nextToken());
            int N = Integer.parseInt(st.nextToken());
            
            if(N % H == 0)
                sb.append((H * 100) + (N / H)).append("\n");
            else
                sb.append(((N % H) * 100) + ((N / H) + 1)).append("\n");
        }
        
        System.out.println(sb);
             
    }
}

 

 

2775번

import java.io.*;
import java.util.*;
 
public class Main {
    
    public static int[][] arr = new int[15][15];
    
    public static void main(String[] args) throws IOException {
        
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
        StringBuilder sb = new StringBuilder();
        
        setArray();
        
        int T = Integer.parseInt(br.readLine());
        
        for(int i = 0; i < T; i++) {
            int k = Integer.parseInt(br.readLine());
            int n = Integer.parseInt(br.readLine());
            sb.append(arr[k][n]).append("\n");
        }
        
        System.out.println(sb);
        
    }
    
    public static void setArray() {
        for (int i = 0; i < 15; i++) {
            arr[i][1] = 1; // i층 1호
            arr[0][i] = i; // 0층 i호
        }
 
        for (int i = 1; i < 15; i++) { 
            for (int j = 2; j < 15; j++) { 
                arr[i][j] = arr[i][j - 1] + arr[i - 1][j];
            }
        }
    }
}

 

 

2839번

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)); 
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        
        int N = Integer.parseInt(br.readLine());
        
        int cnt = 0;
        
        while(true) {
            if(N % 5 == 0) {
                cnt += N / 5;
                System.out.println(cnt);
                break;
            }
            else {
                N -= 3;
                cnt++;
            }
            
            if(N < 0) {
                System.out.println("-1");
                break;
            }
        }
        
    }
}

 

 

10757번

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;
 
public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
        StringTokenizer st;
        
        st = new StringTokenizer(br.readLine()," ");
        
        BigInteger A = new BigInteger(st.nextToken());
        BigInteger B = new BigInteger(st.nextToken());
        
        System.out.println(A.add(B));
    }
}

 

 

1011번

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
 
public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
        StringBuilder sb = new StringBuilder();
        StringTokenizer st;
        
        int T = Integer.parseInt(br.readLine());
        
        for(int i = 0; i < T; i++) {
            st = new StringTokenizer(br.readLine()," ");
            int x = Integer.parseInt(st.nextToken());
            int y = Integer.parseInt(st.nextToken());
            
            int distance = y - x;
            int temp = (int)Math.sqrt(distance);
 
            int cnt = 0;
                        
            if(temp == Math.sqrt(distance)) {
                cnt = 2 * temp - 1;
                sb.append(cnt).append("\n");
            }
            else if(distance <= temp * temp + temp) {
                cnt = 2 * temp;
                sb.append(cnt).append("\n");
            }
            else {
                cnt = 2 * temp + 1;
                sb.append(cnt).append("\n");
            }
            
        }
        System.out.println(sb);
    }
}