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Associated Course(s):
Amazon SDE Test Series

We are given an array of integers and a range, we need to find whether the subarray which falls in this range has values in the form of a mountain or not. All values of the subarray are said to be in the form of a mountain if either all values are increasing or decreasing or first increasing and then decreasing. More formally a subarray [a1, a2, a3 … aN] is said to be in form of a mountain if there exists an integer K, 1 <= K <= N such that,

a1 <= a2 <= a3 .. <= aK >= a(K+1) >= a(K+2) …. >= aN

You have to process **Q** queries. In each query you are given two integer **L** and **R, **denoting starting and last index of the subarrays respectively.

**Input:**

The first line of input contains an integer **T** denoting the number of test cases. Then T test cases follow. Each test case contains an integer **N** denoting the size of the array. The following line contains N space-separated integers forming the array. Next line contains an integer **Q, **denoting the number of queries. For each query, you are given two space-separated integers **L** and **R** in a new line.

**Output:**

For each query, print "**Yes**" (without quotes) if the subarray is in mountain form, otherwise print "**No**" (without quotes) in a new line.

**Expected Time Complexity: **O(N + Q).

**Expected Auxiliary Space: **O(N).

**Constraints:**

1 <= T <= 100

1 <= N, Q <= 10^{5}

1 <= a[i] <= 10^{6}, for each valid i

0 <= L <= R <= N-1

**Example:
Input:**

1

8

2 3 2 4 4 6 3 2

2

0 2

1 3

**Output:**

Yes

No

**Explanation:**

For L = 0 and R = 2, a0 = 2, a1 = 3 and a2 = 2, since they are in the valid order,answer is Yes.

For L = 1 and R = 3, a1 = 3, a2 = 2 and a3 = 4, since a1 > a2 and a2 < a4 the order isn't valid, hence the answer is No.

Author: Ayush Govil 1

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