Minimum absolute difference between two values

65.7% acceptance

Mar 31, 2026

You are given an integer array nums consisting only of 0, 1, and 2. A pair of indices (i, j) is called valid if nums[i] == 1 and nums[j] == 2. Return the minimum absolute difference between i and j among all valid pairs. If no valid pair exists, return -1. The absolute difference between indices i and j is defined as abs(i - j).

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn min_absolute_difference(nums: Vec<i32>) -> i32 {
    let mut ans = i32::MAX;
    let mut last1 = -1i32;
    let mut last2 = -1i32;
    for &x in &nums {
      if x == 1 {
        if last2 >= 0 {
          ans = ans.min((nums.len() as i32).min(last1.max(last2).abs_diff(0) as i32).min((last1 - last2).abs()).min(ans));
          // actually simpler:
        }
        last1 = x; // wrong, need index
      }
    }
    // Redo properly: track closest 2 to the left and closest 1 to the left
    let mut ans2 = i32::MAX;
    let mut last_one: i32 = -1;
    let mut last_two: i32 = -1;
    for i in 0..nums.len() {
      if nums[i] == 1 {
        if last_two >= 0 {
          ans2 = ans2.min((i as i32 - last_two).abs());
        }
        last_one = i as i32;
      } else if nums[i] == 2 {
        if last_one >= 0 {
          ans2 = ans2.min((i as i32 - last_one).abs());
        }
        last_two = i as i32;
      }
    }
    if ans2 == i32::MAX { -1 } else { ans2 }
  }
}