算法与数据结构学习

Chapter2/my.mjs

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+// 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

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+// 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