find the kth smallest element in an array in typescript

index.ts
function quickSelect(arr: number[], k: number): number {
  const pivotIndex = Math.floor(Math.random() * arr.length);
  const pivot = arr[pivotIndex];
  const left = [];
  const right = [];

  for (let i = 0; i < arr.length; i++) {
    if (i === pivotIndex) continue;
    if (arr[i] < pivot) {
      left.push(arr[i]);
    } else {
      right.push(arr[i]);
    }
  }

  if (k <= left.length) {
    return quickSelect(left, k);
  } else if (k === left.length + 1) {
    return pivot;
  } else {
    return quickSelect(right, k - left.length - 1);
  }
}
553 chars
24 lines

index.ts
const arr = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5];
const k = 6;
const kthSmallest = quickSelect(arr, k);
console.log(`The ${k}th smallest element is ${kthSmallest}.`);
164 chars
5 lines

index.ts
The 6th smallest element is 4.
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2 lines