[백준] 16929 - Two Dots (파이썬)

import sys
sys.setrecursionlimit(10**9)
input = sys.stdin.readline
n , m = map(int,input().split())
array = []
for _ in range(n):
    array.append(list(input()))
visit = [[0 for _ in range(m)] for _ in range(n)]
dx = [-1,0,1,0]
dy = [0,1,0,-1]

search = [False]
def DFS(x,y,r,a,b):
    
    if x==a and b==y and visit[x][y] == 2:
        search[0] = True
        
        return
    visit[x][y] += 1
    
    nx = x + dx[r]
    ny = y + dy[r]
    if 0<=nx<n and 0<=ny<m:
        if array[nx][ny] == array[x][y] and visit[nx][ny] != 1:
            DFS(nx,ny,r,a,b)
            visit[nx][ny] = 0
        else:
            for i in range(4):
                if abs(i-r) == 2:
                    continue
                nx = x + dx[i]
                ny = y + dy[i]
                if 0<=nx<n and 0<=ny<m and array[nx][ny] == array[x][y] and visit[nx][ny] != 1:
                    DFS(nx,ny,i,a,b)
                    visit[nx][ny] = 0
                
    else:
        for i in range(4):
            if abs(i-r) == 2:
                continue
            nx = x + dx[i]
            ny = y + dy[i]
            if 0<=nx<n and 0<=ny<m and array[nx][ny] == array[x][y] and visit[nx][ny] != 1:
                DFS(nx,ny,i,a,b)
                visit[nx][ny] = 0

for i in range(n):
    for j in range(m):
        for k in range(4):
            nx = i + dx[k]
            ny = j + dy[k]
            if 0<=nx<n and 0<=ny<m:
                if array[nx][ny] == array[i][j]:
                    visit[i][j] = 1
                    DFS(i,j,k,i,j)
                    visit[i][j] = 0


if search[0]==False:
    print("No")
else:
    print("Yes")