LeetCode-in-Java
2579. Count Total Number of Colored Cells
Medium
There exists an infinitely large two-dimensional grid of uncolored unit cells. You are given a positive integer n, indicating that you must do the following routine for n minutes:
- At the first minute, color any arbitrary unit cell blue.
- Every minute thereafter, color blue every uncolored cell that touches a blue cell.
Below is a pictorial representation of the state of the grid after minutes 1, 2, and 3.
Return the number of colored cells at the end of n minutes.
Example 1:
Input: n = 1
Output: 1
Explanation: After 1 minute, there is only 1 blue cell, so we return 1.
Example 2:
Input: n = 2
Output: 5
Explanation: After 2 minutes, there are 4 colored cells on the boundary and 1 in the center, so we return 5.
Constraints:
1 <= n <= 105
Solution
public class Solution {
public long coloredCells(int n) {
return (long) Math.pow(n, 2) + (long) Math.pow(n - (double) 1, 2);
}
}