README.md

2420. Find All Good Indices

You are given a 0-indexed integer array nums of size n and a positive integer k.

We call an index i in the range k <= i < n - kgood if the following conditions are satisfied:

• The k elements that are just before the index i are in non-increasing order.
• The k elements that are just after the index i are in non-decreasing order.

Return an array of all good indices sorted in increasing order.

Example 1:

Input: nums = [2,1,1,1,3,4,1], k = 2 Output: [2,3] Explanation: There are two good indices in the array: - Index 2. The subarray [2,1] is in non-increasing order, and the subarray [1,3] is in non-decreasing order. - Index 3. The subarray [1,1] is in non-increasing order, and the subarray [3,4] is in non-decreasing order. Note that the index 4 is not good because [4,1] is not non-decreasing. 

Example 2:

Input: nums = [2,1,1,2], k = 2 Output: [] Explanation: There are no good indices in this array. 

Constraints:

• n == nums.length
• 3 <= n <= 105
• 1 <= nums[i] <= 106
• 1 <= k <= n / 2

Solutions (Rust)

1. Solution

implSolution{pubfngood_indices(nums:Vec<i32>,k:i32) -> Vec<i32>{let k = k asusize;let n = nums.len();letmut prefix = vec![0; n];letmut suffix = vec![0; n];letmut count = (1,1);for i in1..n { prefix[i] = count.0; suffix[n - 1 - i] = count.1;if nums[i] <= nums[i - 1]{ count.0 += 1;}else{ count.0 = 1;}if nums[n - 1 - i] <= nums[n - i]{ count.1 += 1;}else{ count.1 = 1;}}(k..n - k).filter(|&i| prefix[i].min(suffix[i]) >= k).map(|i| i asi32).collect()}}