Problem

Given an integer array arr, return true if there are three consecutive odd numbers in the array. Otherwise, return false.

Examples

Example 1:

1
2
3

Input: arr = [2,6,4,1]
Output: false
Explanation: There are no three consecutive odds.

Example 2:

1
2
3

Input: arr = [1,2,34,3,4,5,7,23,12]
Output: true
Explanation: [5,7,23] are three consecutive odds.

Solution

Method 1 - Simply count and iteration

We can follow following steps:

  1. Iterates over the array,
    1. maintaining a counter cnt 
    2. Reset to cnt to 0 whenever an even number is encountered.
    3. If an odd number is found, the counter is incremented.
      1. If the counter reaches 3, indicating three consecutive odd numbers, the method returns true.
  2. If the loop completes without finding such a sequence, the method returns false.

Here is the video explanation:

Code

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14

class Solution {

	public boolean threeConsecutiveOdds(int[] arr) {
		for (int i = 0, cnt = 0; i < arr.length; i++) {
			if (arr[i] % 2 == 0) {
				cnt = 0;
			} else if (++cnt == 3) {
				return true;
			}
		}

		return false;
	}
}

Complexity

  • ⏰ Time complexity: O(n)
  • 🧺 Space complexity: O(1)