### shortestBridge 
from collections import deque
from typing import *
def f_gold(grid: List[List[int]]) -> int:
    def find():
        for i in range(m):
            for j in range(n):
                if grid[i][j] == 1:
                    return i, j
    def dfs(i, j):
        q.append((i, j))
        grid[i][j] = 2
        for a, b in dirs:
            x, y = i + a, j + b
            if 0 <= x < m and 0 <= y < n and grid[x][y] == 1:
                dfs(x, y)
    m, n = len(grid), len(grid[0])
    q = deque()
    dirs = [[0, 1], [0, -1], [1, 0], [-1, 0]]
    i, j = find()
    dfs(i, j)
    ans = -1
    while q:
        ans += 1
        for _ in range(len(q)):
            i, j = q.popleft()
            for a, b in dirs:
                x, y = i + a, j + b
                if 0 <= x < m and 0 <= y < n:
                    if grid[x][y] == 1:
                        return ans
                    if grid[x][y] == 0:
                        grid[x][y] = 2
                        q.append((x, y))
    return 0