16) Code Signal Practice Challenge

I have received a takehome test from a company I’m interviewing with and it’s on the platform Codesignal. Luckily, Codesignal provides me with a practice test I can use to test out its platform! It times me and gives me a challenge:

import IntegerContainerInterface from './integerContainerInterface';
 
export default class IntegerContainer extends IntegerContainerInterface {
  
  nums: number[]
  
  constructor() {
    super();
    this.nums = []
    // TODO: implement
  }
  
  add(value: number): number {
    this.nums.push(value)
    return this.nums.length
  }
  
  delete(value: number): boolean {
    let exists = false
    
    /* failing here
    expect(container.add(555)).to.deep.equal(1);
    expect(container.delete(555)).to.be.true;
    expect(container.delete(555)).to.be.false;
    expect(container.add(555)).to.deep.equal(1);
    expect(container.delete(555)).to.be.true;
    expect(container.delete(555)).to.be.false;
    */
    this.nums = this.nums.map(val => {
      if (val === value && exists === false){
        exists = true
        return null
      }
      return val
    })
    this.nums = this.nums.filter(Boolean)
    return exists
  }
 
  // TODO: implement interface methods here
}

Takeaways from stage one:

• looking at test cases really helped
• forEach, map, sort, know what it returns and how it may mutate instead

Stage 2

import IntegerContainerInterface from './integerContainerInterface';
 
export default class IntegerContainer extends IntegerContainerInterface {
  
  nums: number[]
  
  constructor() {
    super();
    this.nums = []
    // TODO: implement
  }
  
  add(value: number): number {
    this.nums.push(value)
    return this.nums.length
  }
  
  delete(value: number): boolean {
    let exists = false
    
    /* failing here
    expect(container.add(555)).to.deep.equal(1);
    expect(container.delete(555)).to.be.true;
    expect(container.delete(555)).to.be.false;
    expect(container.add(555)).to.deep.equal(1);
    expect(container.delete(555)).to.be.true;
    expect(container.delete(555)).to.be.false;
    */
    this.nums = this.nums.map(val => {
      if (val === value && exists === false){
        exists = true
        return null
      }
      return val
    })
    this.nums = this.nums.filter(Boolean)
    return exists
  }
  
  // [10, 20]
  getMedian(): number | null {
    this.nums = this.nums.sort((a, b) => a - b)
    console.log({nums: this.nums, length: this.nums.length})
    if (this.nums.length === 0) return null
    if (this.nums.length === 1) return this.nums[0]
    if (this.nums.length === 2) return this.nums[0]
    
    // [1, 2, 3, 4] length 4
    // 4/2 = 2, 
    
    if (this.nums.length % 2 === 0){
      return this.nums[(this.nums.length / 2) - 1]
    }
    
    // [1, 2, 3], length is 3, middle index is 1
    // So length - 1 / 2, 
    return this.nums[(this.nums.length - 1) / 2]
    // Return middle number in the .nums array
    // If sequence is even, return the leftmost
    // If it's empty, return null
  }
 
  // TODO: implement interface methods here
}
 
 
 

Man, the mistakes I made were really silly. For even numbers, I got the correct index, but just straight up returned the index rather than the value AT that index.