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https://github.com/krahets/hello-algo.git
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e720aa2d24
* Sync recent changes to the revised Word. * Revised the preface chapter * Revised the introduction chapter * Revised the computation complexity chapter * Revised the chapter data structure * Revised the chapter array and linked list * Revised the chapter stack and queue * Revised the chapter hashing * Revised the chapter tree * Revised the chapter heap * Revised the chapter graph * Revised the chapter searching * Reivised the sorting chapter * Revised the divide and conquer chapter * Revised the chapter backtacking * Revised the DP chapter * Revised the greedy chapter * Revised the appendix chapter * Revised the preface chapter doubly * Revised the figures
97 lines
2.6 KiB
JavaScript
97 lines
2.6 KiB
JavaScript
/**
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* File: array.js
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* Created Time: 2022-11-27
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* Author: IsChristina (christinaxia77@foxmail.com)
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*/
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/* 随机访问元素 */
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function randomAccess(nums) {
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// 在区间 [0, nums.length) 中随机抽取一个数字
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const random_index = Math.floor(Math.random() * nums.length);
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// 获取并返回随机元素
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const random_num = nums[random_index];
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return random_num;
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}
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/* 扩展数组长度 */
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// 请注意，JavaScript 的 Array 是动态数组，可以直接扩展
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// 为了方便学习，本函数将 Array 看作长度不可变的数组
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function extend(nums, enlarge) {
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// 初始化一个扩展长度后的数组
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const res = new Array(nums.length + enlarge).fill(0);
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// 将原数组中的所有元素复制到新数组
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for (let i = 0; i < nums.length; i++) {
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res[i] = nums[i];
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}
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// 返回扩展后的新数组
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return res;
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}
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/* 在数组的索引 index 处插入元素 num */
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function insert(nums, num, index) {
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// 把索引 index 以及之后的所有元素向后移动一位
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for (let i = nums.length - 1; i > index; i--) {
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nums[i] = nums[i - 1];
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}
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// 将 num 赋给 index 处的元素
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nums[index] = num;
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}
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/* 删除索引 index 处的元素 */
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function remove(nums, index) {
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// 把索引 index 之后的所有元素向前移动一位
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for (let i = index; i < nums.length - 1; i++) {
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nums[i] = nums[i + 1];
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}
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}
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/* 遍历数组 */
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function traverse(nums) {
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let count = 0;
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// 通过索引遍历数组
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for (let i = 0; i < nums.length; i++) {
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count += nums[i];
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}
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// 直接遍历数组元素
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for (const num of nums) {
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count += num;
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}
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}
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/* 在数组中查找指定元素 */
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function find(nums, target) {
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for (let i = 0; i < nums.length; i++) {
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if (nums[i] === target) return i;
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}
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return -1;
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}
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/* Driver Code */
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/* 初始化数组 */
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const arr = new Array(5).fill(0);
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console.log('数组 arr =', arr);
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let nums = [1, 3, 2, 5, 4];
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console.log('数组 nums =', nums);
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/* 随机访问 */
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let random_num = randomAccess(nums);
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console.log('在 nums 中获取随机元素', random_num);
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/* 长度扩展 */
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nums = extend(nums, 3);
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console.log('将数组长度扩展至 8 ，得到 nums =', nums);
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/* 插入元素 */
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insert(nums, 6, 3);
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console.log('在索引 3 处插入数字 6 ，得到 nums =', nums);
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/* 删除元素 */
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remove(nums, 2);
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console.log('删除索引 2 处的元素，得到 nums =', nums);
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/* 遍历数组 */
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traverse(nums);
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/* 查找元素 */
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let index = find(nums, 3);
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console.log('在 nums 中查找元素 3 ，得到索引 =', index);
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