9.9头条笔试研发，骗了这么多分不知道是不是人工阅卷

def lengthOfLongestSubstring(s):        
  hash_table = {}
  max_len = -1
  cur_left = 0
        
  for i, c in enumerate(s):
      if c in hash_table and hash_table[c] >= cur_left:
          cur_left = hash_table[c] + 1
      else:
          max_len = max(max_len, i - cur_left + 1)
      hash_table[c] = i
        
  return max_len

import sys

DIRS = [[1, 0], [-1, 0], [0, 1], [0, -1]]


def dfs(g, x, y, visited):
    visited[x][y] = True
    for dir in DIRS:
        temp_x = x + dir[0]
        temp_y = y + dir[1]
        if 0 <= temp_x < len(g) and 0 <= temp_y < len(g[0]) and not visited[temp_x][temp_y] and g[temp_x][temp_y] == 1:
            dfs(g, temp_x, temp_y, visited)
    return


if __name__ == '__main__':
    m = int(sys.stdin.readline().strip())
    graph = []
    for i in range(m):
        temp = list(map(int, sys.stdin.readline().strip().split()))
        if temp:
            graph.append(temp)
    visited = [[False for i in range(len(graph[0]))] for j in range(len(graph))]

    count = 0
    for i in range(len(graph)):
        for j in range(len(graph[0])):
            if graph[i][j] == 1 and not visited[i][j]:
                dfs(graph, i, j, visited)
                count += 1
    print(count)

import sys


def dfs(g, x, y, visited):
    n = len(g)
    visited[y] = True
    for i in range(n):
        if i != y and g[y][i] == 1 and g[x][i] == 0 and not visited[i]:
            g[x][i] = 1
            dfs(g, x, i, visited)
    return


if __name__ == '__main__':
    n = int(sys.stdin.readline().strip())
    m = int(sys.stdin.readline().strip())

    temp_relation = list(map(int, sys.stdin.readline().strip().split()))
    relation = [[0 if i != j else 1 for i in range(n)] for j in range(n)]
    for i in range(m):
        relation[temp_relation[2 * i] - 1][temp_relation[2 * i + 1] - 1] = 1

    for i in range(n):
        visited = [False for i in range(n)]
        for j in range(n):
            if i != j and relation[i][j] == 1 and not visited[j]:
                dfs(relation, i, j, visited)

    relation = list(zip(*relation))
    count = 0
    for i in range(n):
        flag = True
        for j in range(n):
            if relation[i][j] == 0:
                flag = False
                break
        if flag:
            count += 1
    print(count)