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LeetCode solutions

2649. Count Total Number of Colored Cells

My accepted Python solution to LeetCode problem 2649, Count Total Number of Colored Cells, running in 0ms.

  • Difficulty: Medium
  • Python
  • Runtime 0ms
  • Memory 17.1MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 0ms, memory 17.1MB, accepted 2025-12-31.

python
class Solution:
    def coloredCells(self, n: int) -> int:
        # Pattern: 
        # n=1: 1
        # n=2: 1 + 4 = 5
        # n=3: 1 + 4 + 8 = 13
        # n=4: 1 + 4 + 8 + 12 = 25
        # Each step adds 4*(n-1) cells
        # Formula: 1 + 4*(1+2+...+(n-1)) = 1 + 4*(n-1)*n/2 = 1 + 2*(n-1)*n
        # = 1 + 2n^2 - 2n = 2n^2 - 2n + 1
        return 2 * n * n - 2 * n + 1

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