摘要
Title: 3412. 邻域均值
Tag: 二维前缀和
Memory Limit: 64 MB
Time Limit: 1000 ms

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• 题意
• 思路
• 代码

3412. 邻域均值

• 题意

  见原题

• 思路

  二位前缀和即可，注意下标范围即可

• 代码

  '''
  Author: NEFU AB-IN
  Date: 2022-03-17 17:05:12
  FilePath: \ACM\Acwing\3412.py
  LastEditTime: 2022-03-17 17:05:13
  '''
  N = 650
  s = [[0] * N for _ in range(N)]
  a = [[0] * N for _ in range(N)]
  
  n, L, r, t = map(int, input().split())
  for i in range(1, n + 1):
      a[i][1:] = list(map(int, input().split()))
  
  for i in range(1, n + 1):
      for j in range(1, n + 1):
          s[i][j] = s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1] + a[i][j]
  
  ans = 0
  for i in range(1, n + 1):
      for j in range(1, n + 1):
          x1, y1, x2, y2 = max(i - r, 1), max(j - r, 1), min(i + r,
                                                            n), min(j + r, n)
          sum = s[x2][y2] - s[x1 - 1][y2] - s[x2][y1 - 1] + s[x1 - 1][y1 - 1]
          cnt = (x2 - x1 + 1) * (y2 - y1 + 1)
          # print(sum / cnt, sum, x1, y1, x2, y2)
          if sum / cnt <= t:
              ans += 1
  
  print(ans)