LeetCode-in-Java
1248. Count Number of Nice Subarrays
Medium
Given an array of integers nums and an integer k. A continuous subarray is called nice if there are k odd numbers on it.
Return the number of nice sub-arrays.
Example 1:
Input: nums = [1,1,2,1,1], k = 3
Output: 2
Explanation: The only sub-arrays with 3 odd numbers are [1,1,2,1] and [1,2,1,1].
Example 2:
Input: nums = [2,4,6], k = 1
Output: 0
Explanation: There is no odd numbers in the array.
Example 3:
Input: nums = [2,2,2,1,2,2,1,2,2,2], k = 2
Output: 16
Constraints:
1 <= nums.length <= 500001 <= nums[i] <= 10^51 <= k <= nums.length
Solution
public class Solution {
public int numberOfSubarrays(int[] nums, int k) {
int oddLen = 0;
int startIndex = 0;
int num = 0;
int endIndex;
int res = 0;
boolean hasK;
for (int i = 0; i < nums.length; i++) {
hasK = false;
endIndex = i;
if (nums[i] % 2 == 1) {
oddLen++;
}
while (oddLen >= k) {
hasK = true;
if (nums[startIndex++] % 2 == 1) {
oddLen--;
}
num++;
}
res += num;
while (hasK && ++endIndex < nums.length && nums[endIndex] % 2 == 0) {
res += num;
}
num = 0;
}
return res;
}
}