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2438번 문제 : 별 찍기

https://www.acmicpc.net/problem/2438

#include <iostream>
 
using namespace std;
 
int main() {
    int inp;
    cin >> inp;
 
    for (int i = 0; i < inp; i++)
    {
        for(int j = 0; j < i + 1; j++)
        {
            cout << "*";
        }
        cout << endl;
    }
 
    return 0;
}

메모: 

-endl 대신 cout "\n" 사용하면 4ms 빨라짐

2292번 문제 : 벌집

https://www.acmicpc.net/problem/2292

#include <iostream>
using namespace std;
 
int main() {
    int inp;
    cin >> inp;
    int counter = 0;
    int num = 1;
 
    if (inp != 1)
    {
        while (inp > num)
        {
            num = num + 6 * counter;
            counter++;
        }
    }
    else
    {
        counter++;
    }
 
    cout << counter;
 
    return 0;
}

메모: 

-반례 inp : 1때문에 inp !=1 조건문이 필요

1193번 문제 : 분수찾기

https://www.acmicpc.net/problem/1193

#include <iostream>
using namespace std;
 
int main()
{
    int inp;
    cin >> inp;
        
    int total = 1;
    int row = 1;
    while (total < inp)
    {
        row++;
        total += row;
    }
 
    int col = inp - (total - row);
 
    if (row % 2 != 0)//odd
    {
        cout << row - col + 1 << "/" << col;
    }
    else //even
    {
        cout << col << "/" << row - col + 1;
    }
 
    return 0;
}
 

10250번 문제 : ACM 호텔

https://www.acmicpc.net/problem/10250

#include <iostream>
#include <vector>
#include <string>
using namespace std;
 
int main()
{
    int inp;
    cin >> inp;
 
    vector<string> result;
 
    while (inp > 0)
    {
        int h, w, n;
        cin >> h >> w >> n;
 
        string roomNum = "";
        int counter = 1;
        int leftovers = n;
 
        while (leftovers > h) 
        {
            counter++;
            leftovers -= h;
        }
 
        if (counter < 10)
        {
            roomNum += to_string(leftovers);
            roomNum += "0";
            roomNum += to_string(counter);
        }
        else
        {
            roomNum += to_string(leftovers);
            roomNum += to_string(counter);
        }
 
        result.push_back(roomNum);
 
        inp--;
    }
 
    for (auto i : result)
        cout << i << endl;
 
    return 0;
}
 

1924번 문제 : 2007년

https://www.acmicpc.net/problem/1924

#include <iostream>
#include <string>
using namespace std;
 
int main(void) {
 
    string dayName[7] = { "SUN" , "MON", "TUE", "WED", "THU", "FRI", "SAT" };
    int month[13] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
    int totalDays = 0;
    int inputM, inputD;
 
    cin >> inputM >> inputD;
 
    for (int i = 0; i < inputM; i++)
        totalDays += month[i];
    totalDays += inputD;
    int leftover = totalDays % 7;
 
    cout << dayName[leftover];
 
    return 0;
}

2775번 문제 : 부녀회장이 될테야

https://www.acmicpc.net/problem/2775

#include <iostream>
using namespace std;
 
int arr[15][14] = { 0 };
 
int GetNum(int k, int n)
{
    if (k == 0)
        return arr[k][n];
    else
    {
        if (arr[k][n] != 0)
            return arr[k][n];
        else
        {
            for (int i = 0; i <= n; i++)
            {
                arr[k][n] += GetNum(k - 1 , i);
            }
            return arr[k][n];
        }
    }
}
 
int main() {
 
    for (int i = 0; i < 14; i++)
    {
        arr[0][i] = i + 1;
    }
 
    int inp;
    cin >> inp;
 
    while (inp > 0) 
    {
        int a, b;
        cin >> a >> b;
        cout << GetNum(a, b - 1) << endl;
 
        inp--;
    }
    
 
    return 0;
}
 

메모:

-성능을 위해  메모라이제이션 사용

1475번 문제 : 방 번호

https://www.acmicpc.net/problem/1475

#include <iostream>
using namespace std;
 
int main()
{
    int set[10] = { 0 };
    int inp;
    cin >> inp;
 
    if (inp == 0)
    {
        cout << "1" << endl;
        return 0;
    }
    else
    {
        while (inp > 0)
        {
            int temp = inp % 10;
            set[temp] ++;
            inp /= 10;
        }
 
        int maxSet = 0;
        for (int i = 0; i < 10; i++)
        {
            if (i == 6 || i == 9)
                continue;
 
            if (set[i] > maxSet)
                maxSet = set[i];
        }
 
        int sixNineSet;
        if ((set[6] + set[9]) % 2 == 0)
            sixNineSet = (set[6] + set[9]) / 2;
        else
            sixNineSet = (set[6] + set[9]) / 2 + 1;
        if (sixNineSet > maxSet)
            maxSet = sixNineSet;
 
        cout << maxSet << endl;
    }
 
    return 0;
}
 

1475번 문제 : 카잉 달력

https://www.acmicpc.net/problem/6064

#include <iostream>
#include <vector>
using namespace std;
 
int GCD(int a, int b)
{
    if (a % b == 0)
        return b;
 
    return GCD(b, a % b);
}
 
int LCM(int a, int b)
{
    return (a * b) / GCD(a, b);
}
 
int main()
{
    int inp;
    cin >> inp;
 
    vector<int> result;
 
    while (inp > 0)
    {
        int M, N, x, y;
        cin >> M >> N >> x >> y;
 
        int counter = 1;
        int maxYear = LCM(M, N);
        while (true)
        {
            if (x > maxYear || (x - 1) % N + 1 == y)
                break;
 
            x += M;
        }
 
        if (x > maxYear)
            result.push_back(-1);
        else
            result.push_back(x);
 
        inp--;
    }
 
    for (auto i : result)
        cout << i << "\n";
 
    return 0;
}