Official algorithmic problem description and constraints.
There is a circle of red and blue tiles. You are given an array of integers colors and an integer k. The color of tile i is represented by colors[i]:
colors[i] == 0 means that tile i is red.colors[i] == 1 means that tile i is blue.An alternating group is every k contiguous tiles in the circle with alternating colors (each tile in the group except the first and last one has a different color from its left and right tiles).
Return the number of alternating groups.
Note that since colors represents a circle, the first and the last tiles are considered to be next to each other.
Example 1:
Input: colors = [0,1,0,1,0], k = 3
Output: 3
Explanation:
Alternating groups:
Example 2:
Input: colors = [0,1,0,0,1,0,1], k = 6
Output: 2
Explanation:
Alternating groups:
Example 3:
Input: colors = [1,1,0,1], k = 4
Output: 0
Explanation:
Constraints:
3 <= colors.length <= 1050 <= colors[i] <= 13 <= k <= colors.lengthDetailed video explanations, mathematical intuition, and clean C++ implementation code.