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 a of n positive integers. You need to perform the following operation exactly once:
- Choose 2 integers l and r (1≤l≤r≤n) and replace the subarray a[l…r] with the single element: the product of all elements in the subarray (al⋅…⋅ar).
For example, if an operation with parameters l=2,r=4 is applied to the array [5,4,3,2,1], the array will turn into [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 n 个正整数的数组 a。你需要恰好执行一次如下操作:
- 选择两个整数 l 和 r(满足 1≤l≤r≤n),并将子数组 a[l…r] 替换为单个元素:该子数组中所有元素的乘积 (al⋅…⋅ar)。
例如,若对数组 [5,4,3,2,1] 执行参数为 l=2,r=4 的操作,则数组将变为 [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 t (1≤t≤104) — 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 n (1≤n≤2⋅105) — the length of the array a.
The second line of each test case contains n integers a1,a2,…,an (1≤ai≤109).
It is guaranteed that the sum of the values of n for all test cases does not exceed 2⋅105.
每个测试包含多个测试用例。第一行包含一个整数 t(1≤t≤104),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 n(1≤n≤2⋅105),表示数组 a 的长度。
每个测试用例的第二行包含 n 个整数 a1,a2,…,an(1≤ai≤109)。
保证所有测试用例的 n 值之和不超过 2⋅105。
输出格式
For each test case, output 2 integers l and r (1≤l≤r≤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 2 个整数 l 和 r(1≤l≤r≤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=4, the array [1,3,1,3] turns into [1,9], with a sum equal to 10. It is easy to see that by replacing any other segment with a product, the sum will be less than 10.
In the second test case, after applying the operation with parameters l=3,r=4, the array [1,1,2,3] turns into [1,1,6], with a sum equal to 8. It is easy to see that by replacing any other segment with a product, the sum will be less than 8.
In the third test case, it will be optimal to choose any operation with l=r, then the sum of the array will remain 5, 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=4 执行操作后,数组 [1,3,1,3] 变为 [1,9],其和为 10。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 10。
在第二个测试用例中,对参数 l=3,r=4 执行操作后,数组 [1,1,2,3] 变为 [1,1,6],其和为 8。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 8。
在第三个测试用例中,选择任意满足 l=r 的操作是最优的,此时数组的和保持为 5;而执行任意其他操作均会使数组的和减小。
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