hello-algo/codes/javascript/chapter_array_and_linkedlist/array.js
Yudong Jin fcbaf101a4
Several bug fixes and improvements (#945)
* Update Dockerfile for code debugging.

* Format Python code using Black.

* Improve dark theme by defining html classes for the figures, animations and cover images.

* Fix several glossary translation.

* Update a code comment.

* Fix climbing_stairs_backtrack: the pruning should not require the sorted choices list.

* Update the code of array and list traversal.

* Fix a rendering issue of README.md

* Update code of list traversal.

* Fix array_definition.png

* Update README.md

* Fix max_capacity_moving_short_board.png

* Fix array.dart

* Fix array.dart

* Fix array.dart

* Fix array.dart
2023-11-14 21:27:35 +08:00

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JavaScript
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/**
* File: array.js
* Created Time: 2022-11-27
* Author: IsChristina (christinaxia77@foxmail.com)
*/
/* 随机访问元素 */
function randomAccess(nums) {
// 在区间 [0, nums.length) 中随机抽取一个数字
const random_index = Math.floor(Math.random() * nums.length);
// 获取并返回随机元素
const random_num = nums[random_index];
return random_num;
}
/* 扩展数组长度 */
// 请注意JavaScript 的 Array 是动态数组,可以直接扩展
// 为了方便学习,本函数将 Array 看作是长度不可变的数组
function extend(nums, enlarge) {
// 初始化一个扩展长度后的数组
const res = new Array(nums.length + enlarge).fill(0);
// 将原数组中的所有元素复制到新数组
for (let i = 0; i < nums.length; i++) {
res[i] = nums[i];
}
// 返回扩展后的新数组
return res;
}
/* 在数组的索引 index 处插入元素 num */
function insert(nums, num, index) {
// 把索引 index 以及之后的所有元素向后移动一位
for (let i = nums.length - 1; i > index; i--) {
nums[i] = nums[i - 1];
}
// 将 num 赋给 index 处元素
nums[index] = num;
}
/* 删除索引 index 处元素 */
function remove(nums, index) {
// 把索引 index 之后的所有元素向前移动一位
for (let i = index; i < nums.length - 1; i++) {
nums[i] = nums[i + 1];
}
}
/* 遍历数组 */
function traverse(nums) {
let count = 0;
// 通过索引遍历数组
for (let i = 0; i < nums.length; i++) {
count += nums[i];
}
// 直接遍历数组元素
for (const num of nums) {
count += num;
}
}
/* 在数组中查找指定元素 */
function find(nums, target) {
for (let i = 0; i < nums.length; i++) {
if (nums[i] === target) return i;
}
return -1;
}
/* Driver Code */
/* 初始化数组 */
const arr = new Array(5).fill(0);
console.log('数组 arr =', arr);
let nums = [1, 3, 2, 5, 4];
console.log('数组 nums =', nums);
/* 随机访问 */
let random_num = randomAccess(nums);
console.log('在 nums 中获取随机元素', random_num);
/* 长度扩展 */
nums = extend(nums, 3);
console.log('将数组长度扩展至 8 ,得到 nums =', nums);
/* 插入元素 */
insert(nums, 6, 3);
console.log('在索引 3 处插入数字 6 ,得到 nums =', nums);
/* 删除元素 */
remove(nums, 2);
console.log('删除索引 2 处的元素,得到 nums =', nums);
/* 遍历数组 */
traverse(nums);
/* 查找元素 */
let index = find(nums, 3);
console.log('在 nums 中查找元素 3 ,得到索引 =', index);