LeetCode-in-Java
3208. Alternating Groups II
Medium
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] == 0means that tileiis red.colors[i] == 1means that tileiis 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.length
Solution
public class Solution {
public int numberOfAlternatingGroups(int[] colors, int k) {
int i = 0;
int len = 0;
int total = 0;
while (i < colors.length - 1) {
int j = i + 1;
if (colors[j] != colors[i]) {
len = 2;
j++;
while (j < colors.length && colors[j] != colors[j - 1]) {
j++;
len++;
}
if (j == colors.length) {
break;
}
total += Math.max(0, (len - k + 1));
}
i = j;
len = 0;
}
if (colors[0] != colors[colors.length - 1]) {
// if(len == colors.length) {
// return Math.max(0, colors.length);
// }
len = len == 0 ? 2 : len + 1;
int j = 1;
while (j < colors.length && colors[j] != colors[j - 1]) {
j++;
len++;
}
if (j >= k) {
len -= (j - k + 1);
}
}
total += Math.max(0, (len - k + 1));
return total;
}
}