README.md

1497. Check If Array Pairs Are Divisible by k

Given an array of integers arr of even length n and an integer k.

We want to divide the array into exactly n / 2 pairs such that the sum of each pair is divisible by k.

Return trueIf you can find a way to do that orfalseotherwise.

Example 1:

Input: arr = [1,2,3,4,5,10,6,7,8,9], k = 5 Output: true Explanation: Pairs are (1,9),(2,8),(3,7),(4,6) and (5,10). 

Example 2:

Input: arr = [1,2,3,4,5,6], k = 7 Output: true Explanation: Pairs are (1,6),(2,5) and(3,4). 

Example 3:

Input: arr = [1,2,3,4,5,6], k = 10 Output: false Explanation: You can try all possible pairs to see that there is no way to divide arr into 3 pairs each with sum divisible by 10. 

Constraints:

• arr.length == n
• 1 <= n <= 105
• n is even.
• -109 <= arr[i] <= 109
• 1 <= k <= 105

Solutions (Rust)

1. Solution

implSolution{pubfncan_arrange(arr:Vec<i32>,k:i32) -> bool{letmut count = vec![0; k asusize];for&x in&arr { count[x.rem_euclid(k)asusize] += 1;}for i in1..(k asusize + 1) / 2{if count[i] != count[k asusize - i]{returnfalse;}} k % 2 == 1 || count[k asusize / 2] % 2 == 0}}