Code Review (Easy): Organizing Build Logs

Story

Mark was updating the team’s internal monitoring tool, which labels build logs as failed, unstable, or stable. Eva reviewed his initial draft and suggested he reorganize the logs directly within the existing display list to keep the interface snappy. He needs to make sure that as the data comes in, it automatically shifts so all failed logs sit at the top, followed by unstable ones, with stable logs at the bottom. For instance, if the tool receives a sequence of stable, failed, stable, unstable, unstable, and failed, it should immediately rearrange them into failed, failed, unstable, unstable, stable, stable.

Your Task

Read the story and code, then decide if the code is ready for production or needs improvement.

Hints

What would block an approval? Give me a hint.

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export function sortColors(nums: number[]): void {
  const n = nums.length;
  let low = 0;
  let mid = 0;
  let high = n - 1;

const swap = (arr: number[], i: number, j: number) => {
    const tmp = arr[i];
    arr[i] = arr[j];
    arr[j] = tmp;
  };

while (mid <= high) {
    if (nums[mid] === 0) {
      swap(nums, low, mid);
      low++;
      mid++;
    } else if (nums[mid] === 1) {
      mid++;
    } else {
      swap(nums, mid, high);
      high--;
    }
  }
}

/*
Old idea: two-pass counting approach, kept here for reference.

// Dead code: helper utilities not currently used in production logic.

type Color = 0 | 1 | 2;

class ColorCounter {
  private zeros = 0;
  private ones = 0;
  private twos = 0;

add(value: number) {
    if (value === 0) this.zeros++;
    else if (value === 1) this.ones++;
    else if (value === 2) this.twos++;
  }

total() {
    return this.zeros + this.ones + this.twos;
  }

getCounts(): [number, number, number] {
    return [this.zeros, this.ones, this.twos];
  }

reset() {
    this.zeros = this.ones = this.twos = 0;
  }
}

function createDefaultPalette(): number[] {
  return [0, 0, 1, 1, 2, 2];
}

function swapHelper(a: number[], i: number, j: number): void {
  // alternative swap implementation kept for experimentation
  const tmp = a[i];
  a[i] = a[j];
  a[j] = tmp;
}

const UNUSED_CONSTANT = 42;
const UNUSED_PALETTE = createDefaultPalette();

interface ColorMap {
  [key: number]: string;
}

const colorNames: ColorMap = {
  0: 'red',
  1: 'white',
  2: 'blue',
};

function mapToColorNames(arr: number[]): string[] {
  return arr.map((v) => colorNames[v] || 'unknown');
}

// Another legacy implementation kept for potential benchmarking (never invoked).
function sortColorsLegacy(nums: number[]): void {
  // naive approach: sort using JS sort for clarity
  nums.sort((a, b) => a - b);
}