LeetCode Entry

3723. Maximize Sum of Squares of Digits

14.10.2026 medium 2026 kotlin rust

String of max n digits summing up to s

3723. Maximize Sum of Squares of Digits medium substack youtube

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Problem TLDR

String of max n digits summing up to s

Intuition

Take all the nines. Then fit the leftovers.

Approach

• the actual number format is 999+{0..8}000+

Complexity

• Time complexity: \(O(n)\)

• Space complexity: \(O(n)\)

Code

    fun maxSumOfSquares(n: Int, s: Int) =
        if (s>9*n) "" else ("9".repeat(s/9)+s%9).take(n).padEnd(n,'0')

    pub fn max_sum_of_squares(n: i32, s: i32) -> String {
       (0..n*(s<=9*n)as i32).map(|i|((s-9*i).clamp(0,9)+48)as u8 as char).collect()
    }