Cherry (Codeforces 1554A)
Tags: Greedy, greedy

You are given $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$. Find the maximum value of $$$max(a_l, a_{l + 1}, \ldots, a_r) \cdot min(a_l, a_{l + 1}, \ldots, a_r)$$$ over all pairs $$$(l, r)$$$ of integers for which $$$1 \le l < r \le n$$$.

Input: The first line contains a single integer $$$t$$$ ($$$1 \le t \le 10\,000$$$)  — the number of test cases.The first line of each test case contains a single integer $$$n$$$ ($$$2 \le n \le 10^5$$$).The second line of each test case contains $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$ ($$$1 \le a_i \le 10^6$$$).It is guaranteed that the sum of $$$n$$$ over all test cases doesn't exceed $$$3 \cdot 10^5$$$.

Output: For each test case, print a single integer  — the maximum possible value of the product from the statement.

Note: Let $$$f(l, r) = max(a_l, a_{l + 1}, \ldots, a_r) \cdot min(a_l, a_{l + 1}, \ldots, a_r)$$$.In the first test case,   $$$f(1, 2) = max(a_1, a_2) \cdot min(a_1, a_2) = max(2, 4) \cdot min(2, 4) = 4 \cdot 2 = 8$$$.  $$$f(1, 3) = max(a_1, a_2, a_3) \cdot min(a_1, a_2, a_3) = max(2, 4, 3) \cdot min(2, 4, 3) = 4 \cdot 2 = 8$$$.  $$$f(2, 3) = max(a_2, a_3) \cdot min(a_2, a_3) = max(4, 3) \cdot min(4, 3) = 4 \cdot 3 = 12$$$. So the maximum is $$$f(2, 3) = 12$$$.In the second test case, the maximum is $$$f(1, 2) = f(1, 3) = f(2, 3) = 6$$$.

Sample Inputs:
4
3
2 4 3
4
3 2 3 1
2
69 69
6
719313 273225 402638 473783 804745 323328

Sample Outputs:
12
6
4761
381274500335

Solution (Python):
for s in [*open(0)][2::2]:
    a = (*map(int, s.split()),)
    print(max((x * y for (x, y) in zip(a, a[1:]))))

Solution (Python):
for s in [*open(0)][2::2]:
    a = (*map(int, s.split()),)
    print(max((x * y for (x, y) in zip(a, a[1:]))))

Solution (Python):
for s in [*open(0)][2::2]:
    a = (*map(int, s.split()),)
    print(max((x * y for (x, y) in zip(a, a[1:]))))