Design most recently used queue

Array Linked List Divide and Conquer Design Simulation Doubly-Linked List

78.3% acceptance

Mar 31, 2026

338

Design a queue-like data structure that moves the most recently used element to the end of the queue. Implement the MRUQueue class: MRUQueue(int n) constructs the MRUQueue with n elements: [1,2,3,...,n]. int fetch(int k) moves the kth element (1-indexed) to the end of the queue and returns it.

Solution

Rust

Time O(1)

Space O(1)

LeetCode

solution.rs

struct MRUQueue {
  data: Vec<i32>,
}


/** 
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl MRUQueue {

  fn new(n: i32) -> Self {
    MRUQueue { data: (1..=n).collect() }
  }
  
  fn fetch(&mut self, k: i32) -> i32 {
    let idx = (k - 1) as usize;
    let val = self.data.remove(idx);
    self.data.push(val);
    val
  }
}

/*
 * Your MRUQueue object will be instantiated and called as such:
 * let obj = MRUQueue::new(n);
 * let ret_1: i32 = obj.fetch(k);
 */