前端算法

1.冒泡排序（Bubble Sort）

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

const array = [5, 3, 8, 4, 2];
console.log(bubbleSort(array)); // Output: [2, 3, 4, 5, 8]

2.二分查找（Binary Search）

function binarySearch(arr, target) {
  let left = 0;
  let right = arr.length - 1;

  while (left <= right) {
    const mid = Math.floor((left + right) / 2);

    if (arr[mid] === target) {
      return mid;
    } else if (arr[mid] < target) {
      left = mid + 1;
    } else {
      right = mid - 1;
    }
  }

  return -1;
}

const array = [2, 4, 6, 8, 10];
console.log(binarySearch(array, 8)); // Output: 3

3.二叉树的遍历

class TreeNode {
  constructor(val) {
    this.val = val;
    this.left = null;
    this.right = null;
  }
}

function preOrderTraversal(root) {
  const result = [];

  function traverse(node) {
    if (node === null) {
      return;
    }
    
    result.push(node.val);
    traverse(node.left);
    traverse(node.right);
  }

  traverse(root);
  return result;
}

const tree = new TreeNode(1);
tree.left = new TreeNode(2);
tree.right = new TreeNode(3);
console.log(preOrderTraversal(tree)); // Output: [1, 2, 3]