[C++] 1987 - 알파벳

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

1987번: 알파벳

 

 

#include<iostream>
#include<algorithm>
#define endl '\n'
 
using namespace std;
 
char O['z'-'a'+1];
char board[21][21];
int X[4] = {0, 0, 1, -1};
int Y[4] = {1, -1, 0, 0};
int cnt;
int R,C;
 
void dfs(int y, int x, int c);
 
int main(void)
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
 
    cin >> R >> C;
 
    for(int i = 0; i < R; ++i)
        cin >> board[i];
 
    dfs(0, 0, 1);
 
    cout << cnt << endl;
    return 0;
}
 
void dfs(int y, int x, int c)
{
    char tmp = board[y][x];
    O[tmp-'A'] = 1;
    board[y][x] = '\0';
    if(cnt < c)
        cnt = c;
 
    for(int i = 0; i < 4; ++i)
    {
        if(0 <= y+Y[i] && y+Y[i] < R && 0 <= x+X[i] && x+X[i] < C)
        {
            if(!O[board[y+Y[i]][x+X[i]]-'A'] && board[y+Y[i]][x+X[i]])
                dfs(y+Y[i], x+X[i], c+1);
        }
    }
    board[y][x] = tmp;
    O[tmp-'A'] = 0;
}