Question

How to find the maximum distance between two occurrences of same number in array with Rust

Answer 1

fn max_distance(arr: &[i32]) -> usize {
    use std::collections::HashMap;
    let mut index_map = HashMap::new();
    let mut max_dist = 0;

    for (i, &num) in arr.iter().enumerate() {
        if let Some(&first_index) = index_map.get(&num) {
            let dist = i - first_index;
            if dist > max_dist {
                max_dist = dist;
            }
        } else {
            index_map.insert(num, i);
        }
    }

    max_dist
}

fn main() {
    let arr = [7, 1, 4, 3, 1, 5, 3, 4, 9, 1, 3];
    println!(
        "Maximum distance between two occurrences of the same number: {}",
        max_distance(&arr)
    );
}

 
  
/*
run:
  
Maximum distance between two occurrences of the same number: 8
 
*/

 

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