可以用，但是超时了（Python）

def is_valley(grid, x, y, n):
    if grid[x][y] == float('inf') or grid[x][y] >= min_adjacent(grid, x, y, n):
        return False
    stack = [(x, y)]
    grid[x][y] = float('inf')  # 标记为已访问
    size = 1
    while stack:
        i, j = stack.pop()
        for di, dj in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
            ni, nj = i + di, j + dj
            if 0 <= ni < n and 0 <= nj < n and grid[ni][nj] != float('inf'):
                if grid[ni][nj] < min_adjacent(grid, ni, nj, n):
                    stack.append((ni, nj))
                    grid[ni][nj] = float('inf')
                    size += 1
    return size

def min_adjacent(grid, i, j, n):
    values = []
    for di, dj in [(-1, 0), (1, 0), (0, -1), (0, 1)]:
        ni, nj = i + di, j + dj
        if 0 <= ni < n and 0 <= nj < n:
            values.append(grid[ni][nj])
    return min(values) if values else float('inf')

def count_valleys(grid):
    n = len(grid)
    total_valleys = 0
    for i in range(n):
        for j in range(n):
            if grid[i][j] != float('inf'):
                total_valleys += is_valley(grid, i, j, n)
    return total_valleys

def main():
    n = int(input().strip())
    grid = [[float('inf') if c == 'o' else int(c) for c in input().strip()] for _ in range(n)]
    print(count_valleys(grid))

if __name__ == '__main__':
    main()

田亩得太难了