Exercise 2: Sum of Squares - Solution

Idiomatic Solution (using map + sum)

#![allow(unused)]
fn main() {
pub fn sum_of_squares(nums: &[i32]) -> i32 {
    nums.iter().map(|&x| x * x).sum()
}
}

Alternative: Using fold

#![allow(unused)]
fn main() {
pub fn sum_of_squares(nums: &[i32]) -> i32 {
    nums.iter().fold(0, |acc, &x| acc + x * x)
}
}

Alternative: Using for loop (more explicit)

#![allow(unused)]
fn main() {
pub fn sum_of_squares(nums: &[i32]) -> i32 {
    let mut sum = 0;
    for &num in nums {
        sum += num * num;
    }
    sum
}
}

Explanation

Key points:

1. Slices: &[i32] is a borrowed view into a sequence of integers
2. Iterator methods: iter(), map(), and sum() chain together for clean, functional code
3. Closures: |&x| x * x is a closure that takes a reference and squares it
4. Pattern destructuring: |&x| destructures the reference, giving us the value directly
5. Type inference: sum() knows to return i32 based on the context

Why the idiomatic solution is preferred:

• Concise and readable
• No mutable state
• Composable with other iterator methods
• Compiler can optimize well
• Handles empty slices automatically (returns 0)