Number of Subarrays with Bounded Maximum

LeetCode Q 795 - Number of Subarrays with Bounded Maximum

We are given an array A of positive integers, and two positive integers L and R (L <= R).

Return the number of (contiguous, non-empty) subarrays such that the value of the maximum array element in that subarray is at least L and at most R.

Example: Input: A = [2, 1, 4, 3], L = 2, R = 3 ; Output: 3
Explanation: There are three subarrays that meet the requirements: [2], [2, 1], [3].

Note:

• L, R and A[i] will be an integer in the range [0, 10^9].
• The length of A will be in the range of [1, 50000].

Solution :

Code:

public int numSubarrayBoundedMax(int[] A, int L, int R) {
	int left = 0, right = 0, count = 0, res = 0;
	while (right < A.length) {
		if (A[right] >= L && A[right] <= R) {
			res += (right - left + 1); count += right - left + 1; 
		} else if (A[right] < L) {
			res += count;
		} else {
			count = 0; left = right + 1;
		}
	}

	return res;
}