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2117번 홈 방범 서비스 본문

알고리즘 문제/SW Expert Academy

2117번 홈 방범 서비스

parkit 2018. 9. 1. 23:59
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문제 : https://www.swexpertacademy.com/main/code/problem/problemDetail.do?contestProbId=AV5V61LqAf8DFAWu


풀이 : https://www.swexpertacademy.com/main/learn/course/lectureHtmlViewer.do



마름모를 판단할 수 있으면, 쉬운 문제였으나, 마름모를 판단하지 못 한다면 어려운 문제다.


우선, 들어가기 전에 BFS는 마름모 모양으로 퍼져 나간다는 것을 기억하자.


아래의 코드(<BFS>)를 실행해 보면, 각각 <BFS 결과 1><BFS 결과 2>처럼 나온다. 




<BFS>

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#include <iostream>
#include <queue>
#include <cstdio>
#include <vector>
#include <cstring>
#include <string>
#include <math.h>
#include <algorithm>
 
using namespace std;
 
int map[26][26= { 0, };
 
int s = 0, sy = 0, sx = 0;
 
int dy[4= { -1010 };
int dx[4= { 0-101 };
 
void printMap()
{
    for (int i = 0; i < s; i++)
    {
        for (int j = 0; j < s; j++)
        {
            printf("%d", map[i][j]);
        }
 
        printf("\n");
    }
}
 
void BFS(int r, int c)
{
    queue<pair<intint> > q;
 
    bool visit[26][26= { false, };
 
    q.push({ r,c });
 
    map[r][c] = 1;
 
    visit[r][c] = true;
 
    int index = 1;
 
    while (!q.empty())
    {
        int qSize = q.size();
 
        while (qSize--)
        {
            int row = q.front().first;
            int column = q.front().second;
 
            q.pop();
 
            for (int i = 0; i < 4; i++)
            {
                int y = row + dy[i];
                int x = column + dx[i];
 
                if (0 <= y && y < s && 0 <= x && x < s && !visit[y][x])
                {
                    visit[y][x] = true;
                    q.push({ y,x });
                    map[y][x] = 1;
                }
            }
        }
 
        printf("%d번 째 BFS 결과 (아래)\n", index);
 
        printMap();
 
        printf("\n");
 
        ++index;
 
        if (index >= s) break;
    }
}
 
int main(void)
{
    printf("마름모의 크기를 입력하시오. (최대 25) : ");
    scanf("%d"&s);
 
    printf("좌표를 입력하시오. (행, 열) : ");
    scanf("%d %d"&sy, &sx);
 
    BFS(sy, sx);
 
    return 0;
}
cs





<BFS 결과 1>

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좌표를 입력하시오. (행, 열) : 2 2
1번 째 BFS 결과 (아래)
00000
00100
01110
00100
00000
 
2번 째 BFS 결과 (아래)
00100
01110
11111
01110
00100
 
3번 째 BFS 결과 (아래)
01110
11111
11111
11111
01110
 
4번 째 BFS 결과 (아래)
11111
11111
11111
11111
11111
cs




<BFS 결과 2>

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마름모의 크기를 입력하시오. (최대 25) : 20
좌표를 입력하시오. (행, 열) : 0 0
1번 째 BFS 결과 (아래)
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
2번 째 BFS 결과 (아래)
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
3번 째 BFS 결과 (아래)
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
4번 째 BFS 결과 (아래)
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
5번 째 BFS 결과 (아래)
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
6번 째 BFS 결과 (아래)
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
7번 째 BFS 결과 (아래)
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
8번 째 BFS 결과 (아래)
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
9번 째 BFS 결과 (아래)
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
10번 째 BFS 결과 (아래)
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
11번 째 BFS 결과 (아래)
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
12번 째 BFS 결과 (아래)
11111111111110000000
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
13번 째 BFS 결과 (아래)
11111111111111000000
11111111111110000000
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
14번 째 BFS 결과 (아래)
11111111111111100000
11111111111111000000
11111111111110000000
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
15번 째 BFS 결과 (아래)
11111111111111110000
11111111111111100000
11111111111111000000
11111111111110000000
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
16번 째 BFS 결과 (아래)
11111111111111111000
11111111111111110000
11111111111111100000
11111111111111000000
11111111111110000000
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
00000000000000000000
 
17번 째 BFS 결과 (아래)
11111111111111111100
11111111111111111000
11111111111111110000
11111111111111100000
11111111111111000000
11111111111110000000
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
00000000000000000000
 
18번 째 BFS 결과 (아래)
11111111111111111110
11111111111111111100
11111111111111111000
11111111111111110000
11111111111111100000
11111111111111000000
11111111111110000000
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
00000000000000000000
 
19번 째 BFS 결과 (아래)
11111111111111111111
11111111111111111110
11111111111111111100
11111111111111111000
11111111111111110000
11111111111111100000
11111111111111000000
11111111111110000000
11111111111100000000
11111111111000000000
11111111110000000000
11111111100000000000
11111111000000000000
11111110000000000000
11111100000000000000
11111000000000000000
11110000000000000000
11100000000000000000
11000000000000000000
10000000000000000000
cs





<정답 코드>

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#include <iostream>
#include <queue>
#include <cstdio>
#include <vector>
#include <cstring>
#include <string>
#include <math.h>
#include <algorithm>
 
using namespace std;
 
int map[26][26= { 0, };
 
int sy = 0, sx = 0
 
int dy[4= { -1010 };
int dx[4= { 0-101 };
 
int N = 0, M = 0;
 
int max_houseCount = 0;
 
void BFS(int r, int c)
{
    queue<pair<intint> > q;
 
    bool visit[26][26= { false, };
 
    q.push({ r,c });
 
    visit[r][c] = true;
 
    int cnt = map[r][c]; // 집 표시를 1로 해주었으므로, 이것을 단순 '갯수'로 표현할 수 있다.
 
    while (!q.empty()) // queue가 비어있으면, 안 된다.
    {
        for (int K = 1; K <= 2 * N; K++)
        {
            int qSize = q.size();
 
            int price = M*cnt - (K*+ (K - 1)*(K - 1)); // price = (보안회사의 이익)
 
            if (price >= 0 && max_houseCount < cnt)
            {
                // 보안회사가 손해를 보지 않고 = price가 음수'만' 아니면 된다.
                // 서비스 가능한 최대 집의 수 = BFS를 통해 마름모 모양으로 퍼져 나가면서
                //                                K의 범위에 따라 속하는 집의 최대 수
 
                max_houseCount = cnt;
            }
 
            while (qSize--)
            {
                int row = q.front().first;
                int column = q.front().second;
 
                q.pop();
 
                for (int i = 0; i < 4; i++)
                {
                    int y = row + dy[i];
                    int x = column + dx[i];
 
                    if (0 <= y && y < N && 0 <= x && x < N && !visit[y][x])
                    {
                        visit[y][x] = true;
 
                        q.push({ y,x });
 
                        if (map[y][x] == 1++cnt; // 집이면 cnt 1 증가
                    }
                }
            }
        }
    }
}
 
int main(void)
{
    int T = 0;
 
    scanf("%d"&T);
 
    for (int tc = 1; tc <= T; tc++)
    {
        scanf("%d %d"&N, &M);
 
        for (int i = 0; i < N; i++)
        {
            for (int j = 0; j < N; j++)
            {
                scanf("%d"&map[i][j]);
            }
        }
 
        for (int i = 0; i < N; i++)
        {
            for (int j = 0; j < N; j++)
            {
                BFS(i, j);
            }
        }
 
        printf("#%d %d\n", tc, max_houseCount);
 
        max_houseCount = 0;
    }
 
    return 0;
}
cs















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