3206_Alternating_Groups_I.md

3206. Alternating Groups I

Difficulty: easy

Link: https://leetcode.com/problems/alternating-groups-i/

Contains PNG: Yes

PNG Links:

• https://assets.leetcode.com/uploads/2024/05/16/image_2024-05-16_23-53-171.png
• https://assets.leetcode.com/uploads/2024/05/16/image_2024-05-16_23-47-491.png
• https://assets.leetcode.com/uploads/2024/05/16/image_2024-05-16_23-50-441.png
• https://assets.leetcode.com/uploads/2024/05/16/image_2024-05-16_23-48-211.png
• https://assets.leetcode.com/uploads/2024/05/16/image_2024-05-16_23-49-351.png

Problem Statement

There is a circle of red and blue tiles. You are given an array of integers colors. 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.

Every 3 contiguous tiles in the circle with alternating colors (the middle tile has a different color from its left and right tiles) is called an alternating group.

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 = [1,1,1]

Output: 0

Explanation:

Example 2:

Input: colors = [0,1,0,0,1]

Output: 3

Explanation:

Alternating groups:

Constraints:

• 3 <= colors.length <= 100
• 0 <= colors[i] <= 1

Hints

• 1. For each tile, check that the previous and the next tile have different colors from that tile or not.

Code Templates

Cpp

class Solution {
public:
    int numberOfAlternatingGroups(vector<int>& colors) {
        
    }
};

Java

class Solution {
    public int numberOfAlternatingGroups(int[] colors) {
        
    }
}

Python

class Solution:
    def numberOfAlternatingGroups(self, colors: List[int]) -> int: