function bubbleSort(arr) {
  for (let i = 0; i < arr.length; i++) {
    for (let j = 0; j < arr.length - i - 1; j++) {
      if (arr[j] > arr[j + 1]) {
        // 交换位置
        [arr[j], arr[j + 1]] = [arr[j + 1], arr[j]];
      }
    }
  }
  return arr;
}

function selectionSort(arr) {
  for (let i = 0; i < arr.length; i++) {
    let minIndex = i;
    for (let j = i + 1; j < arr.length; j++) {
      if (arr[j] < arr[minIndex]) minIndex = j;
    }
    [arr[i], arr[minIndex]] = [arr[minIndex], arr[i]]; // 交换
  }
  return arr;
}

function insertionSort(arr) {
  for (let i = 1; i < arr.length; i++) {
    let current = arr[i];
    let j = i - 1;
    while (j >= 0 && arr[j] > current) {
      arr[j + 1] = arr[j]; // 后移元素
      j--;
    }
    arr[j + 1] = current; // 插入
  }
  return arr;
}

function quickSort(arr) {
  if (arr.length <= 1) return arr;
  
  const pivot = arr[0];
  const left = [];
  const right = [];

  for (let i = 1; i < arr.length; i++) {
    arr[i] < pivot ? left.push(arr[i]) : right.push(arr[i]);
  }

  return [...quickSort(left), pivot, ...quickSort(right)];
}

function mergeSort(arr) {
  if (arr.length < 2) return arr;
  
  const mid = Math.floor(arr.length / 2);
  const left = arr.slice(0, mid);
  const right = arr.slice(mid);
  
  return merge(mergeSort(left), mergeSort(right));
}

function merge(left, right) {
  const result = [];
  while (left.length && right.length) {
    left[0] <= right[0] 
      ? result.push(left.shift()) 
      : result.push(right.shift());
  }
  return [...result, ...left, ...right];
}