백준 1987 알파벳

https://www.acmicpc.net/problem/1987

1987번: 알파벳

#include <iostream>
#include <stack> 
using namespace std;


char board[21][21] = {};
bool visit[21] = { false };
int Count = 0, result = 0;
int dx[] = { 0, 0, 1, -1 };
int dy[] = { 1, -1, 0, 0 };
int R, C;

void dfs(int x, int y, int cnt)
{
	if (cnt > result)
		result = cnt;
	for (int i = 0; i < 4; i++)
	{
		int nx = x + dx[i];
		int ny = y + dy[i];
		if (nx >= 0 && ny >= 0 && nx < R && ny < C)
		{
			if (visit[board[nx][ny]-65] == false)
			{
				visit[board[nx][ny] - 65] = true;
				dfs(nx, ny, cnt + 1);
				visit[board[nx][ny] - 65] = false;
			}
		}

	}
}
int main(){	

	
	scanf("%d %d", &R, &C);
	char input;
	

	for (int i = 0; i < R; i++)
	{
		for (int j = 0; j < C; j++)
		{
			scanf("%c", &input);
			if (input == '\n')
				--j;
			board[i][j] = input;
		}
	}
	char start = board[0][0];
	visit[start - 65] = true;
	

	dfs(0,0,1);
	printf("%d", result);
	

	return 0;
}