Smallest value of the rearranged number

Math Sorting

53.4% acceptance

Feb 25, 2026

683

You are given an integer num. Rearrange the digits of num such that its value is minimized and it does not contain any leading zeros. Return the rearranged number with minimal value. The sign of the number does not change after rearranging.

Solution

Rust

Time O(n log n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn smallest_number(num: i64) -> i64 {
    if num == 0 {
      return 0;
    }
    let negative = num < 0;
    let mut digits: Vec<u8> = num.abs().to_string().into_bytes();
    if negative {
      // Sort descending to get largest absolute value (most negative)
      digits.sort_unstable_by(|a, b| b.cmp(a));
    } else {
      // Sort ascending, but move leading zeros after the first non-zero digit
      digits.sort_unstable();
      // Find first non-zero digit and swap with index 0
      if let Some(pos) = digits.iter().position(|&b| b != b'0') {
        digits.swap(0, pos);
      }
    }
    let s = String::from_utf8(digits).unwrap();
    let result: i64 = s.parse().unwrap();
    if negative { -result } else { result }
  }
}