refactor: 增加代码示例,代码格式化。

This commit is contained in:
guoli 2022-12-21 19:28:07 +08:00
parent 3b979f8d4e
commit 114fc656d2
3 changed files with 522 additions and 209 deletions

View File

@ -0,0 +1,158 @@
// File: time_complexity.js
// Created Time: 2022-12-21
// Author: leeguooooo (leeguooooo@gmail.com)
/* 常数阶 */
function constant(n) {
let count = 0
const size = 100000
for (let i = 0; i < size; i++) {
count++
}
return count
}
/* 线性阶 */
function linear(n) {
let count = 0
for (let i = 0; i < n; i++) {
count++
}
return count
}
/* 线性阶(遍历数组) */
function arrayTraversal(nums) {
let count = 0
// 循环次数与数组长度成正比
for (let num of nums) {
count++
}
return count
}
/* 平方阶 */
function quadratic(n) {
let count = 0
// 循环次数与数组长度成平方关系
for (let i = 0; i < n; i++) {
for (let j = 0; j < n; j++) {
count++
}
}
return count
}
/* 平方阶(冒泡排序) */
function bubbleSort(nums) {
let count = 0 // 计数器
// 外循环:待排序元素数量为 n-1, n-2, ..., 1
for (let i = nums.length - 1; i > 0; i--) {
// 内循环:冒泡操作
for (let j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j]
nums[j] = nums[j + 1]
nums[j + 1] = tmp
count += 3 // 元素交换包含 3 个单元操作
}
}
}
return count
}
/* 指数阶(循环实现) */
function exponential(n) {
let count = 0,
base = 1
// cell 每轮一分为二,形成数列 1, 2, 4, 8, ..., 2^(n-1)
for (let i = 0; i < n; i++) {
for (let j = 0; j < base; j++) {
count++
}
base *= 2
}
// count = 1 + 2 + 4 + 8 + .. + 2^(n-1) = 2^n - 1
return count
}
/* 指数阶(递归实现)*/
function expRecur(n) {
if (n == 1) return 1
return expRecur(n - 1) + expRecur(n - 1) + 1
}
/* 对数阶(循环实现) */
function logarithmic(n) {
let count = 0
while (n > 1) {
n = n / 2
count++
}
return count
}
/* 对数阶(递归实现)*/
function logRecur(n) {
if (n <= 1) return 0
return logRecur(n / 2) + 1
}
/* 线性对数阶 */
function linearLogRecur(n) {
if (n <= 1) return 1
let count = linearLogRecur(n / 2) + linearLogRecur(n / 2)
for (let i = 0; i < n; i++) {
count++
}
return count
}
/* 阶乘阶(递归实现) */
function factorialRecur(n) {
if (n == 0) return 1
let count = 0
// 从 1 个分裂出 n 个
for (let i = 0; i < n; i++) {
count += factorialRecur(n - 1)
}
return count
}
/* 生成一个数组,元素为 { 1, 2, ..., n },顺序被打乱 */
function randomNumbers(n) {
// 生成数组 nums = { 1, 2, 3, ..., n }
let nums = [...Array(n).keys()].map(i => i + 1);
shuffle(nums);
return nums;
}
/* 查找数组 nums 中数字 1 所在索引 */
function findOne(nums) {
for (let i = 0; i < nums.length; i++) {
if (nums[i] === 1) return i;
}
return -1;
}
/* 随机打乱数组元素 */
function shuffle(arr) {
let n = arr.length;
for (let i = 0; i < n; i++) {
let j = Math.floor(Math.random() * n);
[arr[i], arr[j]] = [arr[j], arr[i]];
}
}
/* Driver Code */
; (function main() {
for (let i = 0; i < 10; i++) {
let n = 100;
let nums = randomNumbers(n);
let index = findOne(nums);
console.log("\n数组 [ 1, 2, ..., n ] 被打乱后 =", nums);
console.log("数字 1 的索引为", index);
}
})()

View File

@ -0,0 +1,157 @@
// File: time_complexity.ts
// Created Time: 2022-12-21
// Author: leeguooooo (leeguooooo@gmail.com)
/* 常数阶 */
function constant(n: number): number {
let count = 0
const size = 100000
for (let i = 0; i < size; i++) {
count++
}
return count
}
/* 线性阶 */
function linear(n: number): number {
let count = 0
for (let i = 0; i < n; i++) {
count++
}
return count
}
/* 线性阶(遍历数组) */
function arrayTraversal(nums: number[]) {
let count = 0
// 循环次数与数组长度成正比
for (let num of nums) {
count++
}
return count
}
/* 平方阶 */
function quadratic(n: number) {
let count = 0
// 循环次数与数组长度成平方关系
for (let i = 0; i < n; i++) {
for (let j = 0; j < n; j++) {
count++
}
}
return count
}
/* 平方阶(冒泡排序) */
function bubbleSort(nums: number[]) {
let count = 0 // 计数器
// 外循环:待排序元素数量为 n-1, n-2, ..., 1
for (let i = nums.length - 1; i > 0; i--) {
// 内循环:冒泡操作
for (let j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j]
nums[j] = nums[j + 1]
nums[j + 1] = tmp
count += 3 // 元素交换包含 3 个单元操作
}
}
}
return count
}
/* 指数阶(循环实现) */
function exponential(n: number) {
let count = 0,
base = 1
// cell 每轮一分为二,形成数列 1, 2, 4, 8, ..., 2^(n-1)
for (let i = 0; i < n; i++) {
for (let j = 0; j < base; j++) {
count++
}
base *= 2
}
// count = 1 + 2 + 4 + 8 + .. + 2^(n-1) = 2^n - 1
return count
}
/* 指数阶(递归实现)*/
function expRecur(n: number) {
if (n == 1) return 1
return expRecur(n - 1) + expRecur(n - 1) + 1
}
/* 对数阶(循环实现) */
function logarithmic(n: number) {
let count = 0
while (n > 1) {
n = n / 2
count++
}
return count
}
/* 对数阶(递归实现)*/
function logRecur(n: number) {
if (n <= 1) return 0
return logRecur(n / 2) + 1
}
/* 线性对数阶 */
function linearLogRecur(n: number) {
if (n <= 1) return 1
let count = linearLogRecur(n / 2) + linearLogRecur(n / 2)
for (let i = 0; i < n; i++) {
count++
}
return count
}
/* 阶乘阶(递归实现) */
function factorialRecur(n: number) {
if (n == 0) return 1
let count = 0
// 从 1 个分裂出 n 个
for (let i = 0; i < n; i++) {
count += factorialRecur(n - 1)
}
return count
}
/* 生成一个数组,元素为 { 1, 2, ..., n },顺序被打乱 */
function randomNumbers(n: number): number[] {
// 生成数组 nums = { 1, 2, 3, ..., n }
let nums = [...Array(n).keys()].map((i) => i + 1)
shuffle(nums)
return nums
}
/* 查找数组 nums 中数字 1 所在索引 */
function findOne(nums: number[]): number {
for (let i = 0; i < nums.length; i++) {
if (nums[i] === 1) return i
}
return -1
}
/* 随机打乱数组元素 */
function shuffle(arr: number[]) {
let n = arr.length
for (let i = 0; i < n; i++) {
let j = Math.floor(Math.random() * n)
;[arr[i], arr[j]] = [arr[j], arr[i]]
}
}
/* Driver Code */
; (function main() {
for (let i = 0; i < 10; i++) {
let n = 100
let nums = randomNumbers(n)
let index = findOne(nums)
console.log('\n数组 [ 1, 2, ..., n ] 被打乱后 =', nums)
console.log('数字 1 的索引为', index)
}
})()

View File

@ -349,8 +349,7 @@ $$
a = a + 1 // +1
a = a * 2 // +1
// 循环 n 次
for (let i = 0; i < n; i++) {
// +1每轮都执行 i ++
for (let i = 0; i < n; i++) { // +1每轮都执行 i ++
console.log(0) // +1
}
}
@ -364,8 +363,7 @@ $$
a = a + 1 // +1
a = a * 2 // +1
// 循环 n 次
for (let i = 0; i < n; i++) {
// +1每轮都执行 i ++
for (let i = 0; i < n; i++) { // +1每轮都执行 i ++
console.log(0) // +1
}
}
@ -1948,7 +1946,7 @@ $$
}
/* Driver Code */
;(function main() {
; (function main() {
for (let i = 0; i < 10; i++) {
let n = 100;
let nums = randomNumbers(n);
@ -1988,7 +1986,7 @@ $$
}
/* Driver Code */
;(function main() {
; (function main() {
for (let i = 0; i < 10; i++) {
let n = 100
let nums = randomNumbers(n)