백준 1987 알파벳 C++

문제

www.acmicpc.net/problem/1987

1987번: 알파벳

코드

#include <bits/stdc++.h>

using namespace std;

int r, c, answer = 1, arr[21][21], alphabet[26], dy[] = { -1, 0, 1, 0 }, dx[] = { 0, 1, 0, -1 };
char ch;

void input()
{
	cin >> r >> c;
	for (int i = 0; i < r; i++)
	{
		for (int j = 0; j < c; j++)
		{
			cin >> ch;
			arr[i][j] = ch - 'A';
		}
	}
}

int go(int y, int x, int num)
{
	for (int i = 0; i < 4; i++)
	{
		int ny = dy[i] + y;
		int nx = dx[i] + x;
		if (ny >= r || ny < 0 || nx >= c || nx < 0 || alphabet[arr[ny][nx]])
			continue;

		alphabet[arr[ny][nx]] = 1;
		answer = max(answer, go(ny ,nx, num+1));
		alphabet[arr[ny][nx]] = 0;
	}

	return num;
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);

	input();

	alphabet[arr[0][0]] = 1;
	go(0, 0, 1);
	cout << answer << '\n';
	return 0;
}