LeetCode Entry

2778. Sum of Squares of Special Elements

11.10.2026 easy 2026 kotlin rust

Sum of squares at positions divisible by size

2778. Sum of Squares of Special Elements easy substack youtube

https://dmitrysamoylenko.com/leetcode/

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Problem TLDR

Sum of squares at positions divisible by size

Intuition

Brute force works. Optimization: check only the first sqrt(n) positions, and for each use i and size/i

Approach

• this problem requires attention to what is actually asked to do

Complexity

• Time complexity: \(O(n)\)

• Space complexity: \(O(1)\)

Code

    fun sumOfSquares1(n: IntArray)=
    n.indices.sumOf{(1-(n.size%(it+1)).sign)*n[it]*n[it]}

    pub fn sum_of_squares(n: Vec<i32>) -> i32 {
        n.iter().zip(1..).map(|(x,i)|x*x*((n.len()%i==0)as i32)).sum()
    }