CF1872G.Replace With Product

普及+/提高

通过率:0%

时间限制:1.00s

内存限制:256MB

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题目描述

Given an array aa of nn positive integers. You need to perform the following operation exactly once:

  • Choose 22 integers ll and rr (1≤l≤r≤n1 \le l \le r \le n) and replace the subarray a[l…r]a[l \ldots r] with the single element: the product of all elements in the subarray (al⋅…⋅ar)(a_l \cdot \ldots \cdot a_r).

For example, if an operation with parameters l=2,r=4l = 2, r = 4 is applied to the array [5,4,3,2,1][5, 4, 3, 2, 1], the array will turn into [5,24,1][5, 24, 1].

Your task is to maximize the sum of the array after applying this operation. Find the optimal subarray to apply this operation.

给定一个包含 nn 个正整数的数组 aa。你需要恰好执行一次如下操作:

  • 选择两个整数 ll 和 rr(满足 1≤l≤r≤n1 \le l \le r \le n),并将子数组 a[l…r]a[l \ldots r] 替换为单个元素:该子数组中所有元素的乘积 (al⋅…⋅ar)(a_l \cdot \ldots \cdot a_r)。

例如,若对数组 [5,4,3,2,1][5, 4, 3, 2, 1] 执行参数为 l=2,r=4l = 2, r = 4 的操作,则数组将变为 [5,24,1][5, 24, 1]。

你的任务是使执行该操作后的数组元素之和尽可能大。请找出应执行该操作的最优子数组。

输入格式

Each test consists of multiple test cases. The first line contains a single integer tt (1≤t≤1041 \le t \le 10^4) — the number of test cases. This is followed by the description of the test cases.

The first line of each test case contains a single number nn (1≤n≤2⋅1051 \le n \le 2 \cdot 10^5) — the length of the array aa.

The second line of each test case contains nn integers a1,a2,…,ana_1, a_2, \ldots, a_n (1≤ai≤1091 \le a_i \le 10^9).

It is guaranteed that the sum of the values of nn for all test cases does not exceed 2⋅1052 \cdot 10^5.

每个测试包含多个测试用例。第一行包含一个整数 tt(1≤t≤1041 \le t \le 10^4),表示测试用例的数量。随后是各测试用例的描述。

每个测试用例的第一行包含一个整数 nn(1≤n≤2⋅1051 \le n \le 2 \cdot 10^5),表示数组 aa 的长度。

每个测试用例的第二行包含 nn 个整数 a1,a2,…,ana_1, a_2, \ldots, a_n(1≤ai≤1091 \le a_i \le 10^9)。

保证所有测试用例的 nn 值之和不超过 2⋅1052 \cdot 10^5。

输出格式

For each test case, output 22 integers ll and rr (1≤l≤r≤n1 \le l \le r \le n) — the boundaries of the subarray to be replaced with the product.

If there are multiple solutions, output any of them.

对于每个测试用例,输出 22 个整数 ll 和 rr(1≤l≤r≤n1 \le l \le r \le n)—— 表示需要被替换为乘积的子数组的边界。

如果存在多个解,输出其中任意一个即可。

输入输出样例

  • 输入#1

    9
    4
    1 3 1 3
    4
    1 1 2 3
    5
    1 1 1 1 1
    5
    10 1 10 1 10
    1
    1
    2
    2 2
    3
    2 1 2
    4
    2 1 1 3
    6
    2 1 2 1 1 3

    输出#1

    2 4
    3 4
    1 1
    1 5
    1 1
    1 2
    2 2
    4 4
    1 6

说明/提示

In the first test case, after applying the operation with parameters l=2,r=4l = 2, r = 4, the array [1,3,1,3][1, 3, 1, 3] turns into [1,9][1, 9], with a sum equal to 1010. It is easy to see that by replacing any other segment with a product, the sum will be less than 1010.

In the second test case, after applying the operation with parameters l=3,r=4l = 3, r = 4, the array [1,1,2,3][1, 1, 2, 3] turns into [1,1,6][1, 1, 6], with a sum equal to 88. It is easy to see that by replacing any other segment with a product, the sum will be less than 88.

In the third test case, it will be optimal to choose any operation with l=rl = r, then the sum of the array will remain 55, and when applying any other operation, the sum of the array will decrease.

在第一个测试用例中,对参数 l=2,r=4l = 2, r = 4 执行操作后,数组 [1,3,1,3][1, 3, 1, 3] 变为 [1,9][1, 9],其和为 1010。容易看出,若将任意其他子段替换为其乘积,所得数组的和均小于 1010。

在第二个测试用例中,对参数 l=3,r=4l = 3, r = 4 执行操作后,数组 [1,1,2,3][1, 1, 2, 3] 变为 [1,1,6][1, 1, 6],其和为 88。容易看出,若将任意其他子段替换为其乘积,所得数组的和均小于 88。

在第三个测试用例中,选择任意满足 l=rl = r 的操作是最优的,此时数组的和保持为 55;而执行任意其他操作均会使数组的和减小。

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