算法与数据结构学习

Chapter2/my.mjs

@@ -0,0 +1,51 @@
+// 对数组进行复制，非引用赋值
+function copy(arr) {
+  const arr2 = [];
+  const len = arr.length;
+  for (let i = 0; i < len; i++) {
+    arr2[i] = arr[i];
+  }
+
+  return arr2;
+}
+
+// 关于sort排序
+// 数字排序方式，从小到大升序排列
+// sort函数接受的排序方法，返回的值应当为负数、0、正数，排序也按照这个顺序排序
+function sortNumber(a, b) {
+  return a - b;
+}
+
+// 获取奇数
+function isOdd(num) {
+  return num % 2 !== 0;
+}
+
+// 获取偶数
+function isEven(num) {
+  return num % 2 === 0;
+}
+
+const nums = [];
+for (let i = 0; i < 20; i++) {
+  nums[i] = i + 1;
+}
+
+const oddList = nums.filter(isOdd);
+const evenList = nums.filter(isEven);
+
+console.log(oddList);
+console.log(evenList);
+
+// 创建二维数组（表格）
+Array.matrix = function(numrows, numcols, initval) {
+  const arr = [];
+  for (let i = 0; i < numrows; i++) {
+    const columns = [];
+    for (let j = 0; j < numcols; j++) {
+      columns[j] = initval;
+    }
+    arr[i] = columns;
+  }
+  return arr;
+}

Chapter2/test.mjs

@@ -0,0 +1,64 @@
+// 1
+// 创建一个记录学生成绩的对象，提供一个添加成绩的方法，以及一个显示学生平均成绩的方法。
+function createTranscript() {
+  this.gradeList = [];
+  this.add = (num) => {
+    this.gradeList.push(num);
+  };
+  this.calcAvge = () => {
+    const sum = this.gradeList.reduce((sum, grade) => {
+      sum += grade;
+      return sum;
+    }, 0);
+    return sum / this.gradeList.length;
+  };
+}
+
+const transcript1 = new createTranscript();
+transcript1.add(120);
+transcript1.add(80);
+console.log(transcript1.calcAvge());
+
+// 2
+// 将一组单词存储在一个数组中，并按正序和倒序分别显示这些单词
+const list = ["fan", "sheng", "fa", "lan", "xiu", "ping"];
+for (let i = 0; i < list.length; i++) {
+  console.log(list[i]);
+}
+console.log("--------------------------")
+for (let i = list.length - 1; i >= 0; i--) {
+  console.log(list[i]);
+}
+
+// 3
+function weekTemps() {
+  this.dataStore = [];
+  for (let i = 0; i < 12; i++) {
+    this.dataStore.push([])
+  }
+  this.add = add;
+  this.average = average;
+}
+
+function add(month, temp) {
+  this.dataStore[month].push(temp);
+}
+
+function average() {
+  var total = 0;
+  for (var i = 0; i < this.dataStore.length; ++i) {
+     total += this.dataStore[i];
+  }
+  return total / this.dataStore.length;
+}
+
+var thisWeek = new weekTemps();
+thisWeek.add(52);
+thisWeek.add(55);
+thisWeek.add(61);
+thisWeek.add(65);
+thisWeek.add(55);
+thisWeek.add(50);
+thisWeek.add(52);
+thisWeek.add(49);
+print(thisWeek.average()); // displays 54.875

Chapter3/list.mjs

@@ -0,0 +1,143 @@
+function List() {
+  this.listSize = 0;
+  this.pos = 0;
+  this.dataStore = [];
+  this.clear = clear;
+  this.find = find;
+  this.toString = toString;
+  this.insert = insert;
+  this.append = append;
+  this.remove = remove;
+  this.front = front;
+  this.end = end;
+  this.prev = prev;
+  this.next = next;
+  this.hasNext = hasNext;
+  this.hasPrev = hasPrev;
+  this.length = length;
+  this.currPos = currPos;
+  this.moveTo = moveTo;
+  this.getElement = getElement;
+  this.contains = contains;
+}
+
+function append(element) {
+  // 元素追加后，listSize 自增
+  this.dataStore[this.listSize++] = element;
+}
+
+function find(element) {
+  for (let i = 0; i < this.dataStore.length; i++) {
+    if (this.dataStore[i] === element) {
+      return i;
+    }
+  }
+  return -1;
+}
+
+function remove(element) {
+  const foundAt = this.find(element);
+  if (foundAt > -1) {
+    this.dataStore.splice(foundAt, 1);
+    --this.listSize;
+    return true;
+  }
+  return false;
+}
+
+function length() {
+  return this.listSize;
+}
+
+function toString() {
+  return this.dataStore;
+}
+
+function insert(element, after) {
+  const insertPos = this.find(after);
+  if (insertPos > -1) {
+    this.dataStore.splice(after, 0, element);
+    ++this.listSize;
+    return true;
+  }
+  return false;
+}
+
+function clear() {
+  delete this.dataStore;
+  this.dataStore.length = 0;
+  this.listSize = this.pos = 0;
+}
+
+function contains(element) {
+  for (let i = 0; i < this.dataStore.length; i++) {
+    if (this.dataStore[i] === element) {
+      return true
+    }
+  }
+  return false;
+}
+
+function front() {
+  this.pos = 0;
+}
+
+function end() {
+  this.pos = this.listSize - 1;
+}
+
+function prev() {
+  --this.pos;
+}
+
+function next() {
+  if (this.pos < this.listSize) {
+    this.pos++;
+  }
+}
+
+function currPos() {
+  return this.pos;
+}
+
+function moveTo(position) {
+  this.pos = position;
+}
+
+function getElement() {
+  return this.dataStore[this.pos];
+}
+
+function hasNext() {
+  return this.pos < this.listSize;
+}
+
+function hasPrev() {
+  return this.pos >= 0;
+}
+
+const names = new List();
+names.append('Clayton');
+names.append('Raymond');
+names.append('Cynthia');
+names.append('Jennifer');
+names.append('Bryan');
+names.append('Danny');
+names.front();
+// console.log(names.getElement());
+names.next();
+// console.log(names.getElement());
+names.next();
+names.next();
+names.prev();
+// console.log(names.getElement());
+
+// 从前往后遍历
+for (names.front(); names.hasNext(); names.next()) {
+  console.log(names.getElement());
+}
+console.log('------------------------------------')
+// 从后往前遍历
+for (names.end(); names.hasPrev(); names.prev()) {
+  console.log(names.getElement());
+}

Chapter3/movies.mjs

@@ -0,0 +1,192 @@
+function List() {
+  this.listSize = 0;
+  this.pos = 0;
+  this.dataStore = [];
+  this.clear = clear;
+  this.find = find;
+  this.toString = toString;
+  this.insert = insert;
+  this.append = append;
+  this.remove = remove;
+  this.front = front;
+  this.end = end;
+  this.prev = prev;
+  this.next = next;
+  this.hasNext = hasNext;
+  this.hasPrev = hasPrev;
+  this.length = length;
+  this.currPos = currPos;
+  this.moveTo = moveTo;
+  this.getElement = getElement;
+  this.contains = contains;
+  this.appendWhenBig = appendWhenBig;
+  this.appendWhenSmall = appendWhenSmall;
+}
+
+function append(element) {
+  // 元素追加后，listSize 自增
+  this.dataStore[this.listSize++] = element;
+}
+
+function find(element) {
+  for (let i = 0; i < this.dataStore.length; i++) {
+    if (this.dataStore[i] === element) {
+      return i;
+    }
+  }
+  return -1;
+}
+
+function remove(element) {
+  const foundAt = this.find(element);
+  if (foundAt > -1) {
+    this.dataStore.splice(foundAt, 1);
+    --this.listSize;
+    return true;
+  }
+  return false;
+}
+
+function length() {
+  return this.listSize;
+}
+
+function toString() {
+  return this.dataStore;
+}
+
+function insert(element, after) {
+  const insertPos = this.find(after);
+  if (insertPos > -1) {
+    this.dataStore.splice(after, 0, element);
+    ++this.listSize;
+    return true;
+  }
+  return false;
+}
+
+function clear() {
+  delete this.dataStore;
+  this.dataStore.length = 0;
+  this.listSize = this.pos = 0;
+}
+
+function contains(element) {
+  for (let i = 0; i < this.dataStore.length; i++) {
+    if (this.dataStore[i] === element) {
+      return true
+    }
+  }
+  return false;
+}
+
+function front() {
+  this.pos = 0;
+}
+
+function end() {
+  this.pos = this.listSize - 1;
+}
+
+function prev() {
+  --this.pos;
+}
+
+function next() {
+  if (this.pos < this.listSize) {
+    this.pos++;
+  }
+}
+
+function currPos() {
+  return this.pos;
+}
+
+function moveTo(position) {
+  this.pos = position;
+}
+
+function getElement() {
+  return this.dataStore[this.pos];
+}
+
+function hasNext() {
+  return this.pos < this.listSize;
+}
+
+function hasPrev() {
+  return this.pos >= 0;
+}
+
+function appendWhenBig(element) {
+  let flag = true;
+  for (this.front(); this.hasNext(); this.next()) {
+    if (this.getElement() > element) {
+      flag = false;
+    }
+  }
+
+  if (flag) {
+    this.append(element);
+  }
+}
+
+function appendWhenSmall(element) {
+  let flag = true;
+  for (this.front(); this.hasNext(); this.next()) {
+    if (this.getElement() < element) {
+      flag = false;
+    }
+  }
+
+  if (flag) {
+    this.append(element);
+  }
+}
+
+function displayList(list) {
+  for (list.front(); list.currPos() < list.length(); list.next()) {
+    console.log(list.getElement());
+  }
+}
+
+function Customer(name, movie) {
+  this.name = name;
+  this.movie = movie;
+}
+
+function checkout(name, movie, movieList, customerList) {
+  if (movieList.contains(movie)) {
+    const c = new Customer(name, movie);
+    customerList.append(c);
+    movieList.remove(movie);
+  } else {
+    console.log(movie + ' is not available.');
+  }
+}
+
+const movies = ['大室家 亲爱的姐妹们', '紫罗兰永恒花园', '牵牛花与加濑同学。', '利兹与青鸟', '摇曳百合 夏日时光！'];
+const movieList = new List();
+const customers = new List();
+for (let i = 0; i < movies.length; i++) {
+  movieList.append(movies[i]);
+}
+console.log('Available moviews: \n');
+displayList(movieList);
+
+const readline = require('readline');
+const rl = readline.createInterface({
+  input: process.stdin,
+  output: process.stdout
+});
+
+rl.question('Enter your name: ', (name) => {
+   rl.question('What movie would you like?', (movie) => {
+     checkout(name, movie, movieList, customers);
+     console.log('Customer Rentals: ');
+     displayList(customers);
+     console.log('Movies Now Available');
+     displayList(movieList);
+     rl.close();
+   })
+})

Chapter4/stack.mjs

@@ -0,0 +1,29 @@
+function push(element) {
+  this.dataSource[this.top++] = element;
+}
+
+function pop() {
+  return this.dataSource[--this.top];
+}
+
+function peek() {
+  return this.dataSource[this.top - 1];
+}
+
+function length() {
+  return this.top;
+}
+
+function clear() {
+  this.top = 0;
+}
+
+export default function Stack() {6
+  this.dataSource = [];
+  this.top = 0;
+  this.push = push;
+  this.pop = pop;
+  this.peek = peek;
+  this.length = length;
+  this.clear = clear;
+}

Chapter4/test1.mjs

@@ -0,0 +1,20 @@
+import Stack from "./stack.mjs";
+// 找出缺失的括号
+function findMissingParentheses(expression) {
+  const stack = new Stack();
+  const expressionList = expression.split('');
+  for (let i = 0; i < expressionList.length; i++) { 
+    const char = expressionList[i];
+    if (char === '(') {
+      stack.push(i);
+    }
+    if (char === ')') {
+      stack.pop();
+    }
+  }
+  if (stack.length() > 0) {
+    console.log('missing parent index:', stack.pop());
+  }
+}
+
+findMissingParentheses('2.3 + 23 / 12 + (3.14159 x 0.24')

Chapter4/test2.mjs

@@ -0,0 +1,111 @@
+import Stack from "./stack.mjs";
+
+function infixToPostfix(infixExpression) {
+  const stack1 = new Stack();
+  const stack2 = new Stack();
+
+  function warOperator(operator1, operator2) {
+    if (operator2 === undefined || operator2 === "(") {
+      stack1.push(operator1);
+    } else {
+      if (["x", "/"].includes(operator1) && ["+", "-"].includes(operator2)) {
+        stack1.push(operator1);
+      } else {
+        const top = stack1.pop();
+        stack2.push(top);
+        const nextOperator = stack1.peek();
+        warOperator(operator1, nextOperator);
+      }
+    }
+  }
+
+  const dealInfixExpression = infixExpression.replaceAll(" ", "");
+
+  let numStr = "";
+  for (let i = 0; i < dealInfixExpression.length; i++) {
+    const char = dealInfixExpression[i];
+    if (["+", "-", "x", "/"].includes(char)) {
+      if (numStr.length > 0) {
+        stack2.push(numStr);
+        numStr = "";
+      }
+      const topOperator = stack1.peek();
+      warOperator(char, topOperator);
+    } else if (["(", ")"].includes(char)) {
+      if (numStr.length > 0) {
+        stack2.push(numStr);
+        numStr = "";
+      }
+      if (char === "(") {
+        stack1.push(char);
+      } else {
+        while (stack1.length()) {
+          let operator = stack1.pop();
+          if (operator === "(") {
+            break;
+          }
+          stack2.push(operator);
+        }
+      }
+    } else {
+      numStr += char;
+      if (i === dealInfixExpression.length - 1) {
+        stack2.push(numStr);
+      }
+    }
+  }
+
+  while (stack1.length()) {
+    stack2.push(stack1.pop());
+  }
+
+  const postfixExpression = [];
+  while (stack2.length()) {
+    postfixExpression.push(stack2.pop());
+  }
+  postfixExpression.reverse();
+  return postfixExpression;
+}
+
+function calc(num1, num2, operator) {
+  const n1 = Number(num1);
+  const n2 = Number(num2);
+  let result;
+  switch (operator) {
+    case "+":
+      result = n1 + n2;
+      break;
+    case "-":
+      result = n1 - n2;
+      break;
+    case "x":
+      result = n1 * n2;
+      break;
+    case "/":
+      result = n1 / n2;
+      break;
+  }
+  return result;
+}
+
+function calculate(postfixExpression) {
+  const stack = new Stack();
+  for (let i = 0; i < postfixExpression.length; i++) {
+    const element = postfixExpression[i];
+    if (["+", "-", "x", "/"].includes(element)) {
+      const num2 = stack.pop();
+      const num1 = stack.pop();
+      stack.push(calc(num1, num2, element));
+    } else {
+      stack.push(element);
+    }
+  }
+
+  return stack.pop();
+}
+
+const expression = "12+((2.1+3) x45.2)-5.22";
+const postfixExpression = infixToPostfix(expression);
+console.log(postfixExpression);
+const result = calculate(postfixExpression);
+console.log(result);