[김세림] 2주차 과제 (진행중)

problem-1-1/problem-1-1.test.js

@@ -1,4 +1,58 @@
+class Node {
+  item;
+  next;
+}
+
 class Bag {
+  _n;
+  _first;
+
+  constructor() {
+    this._n = 0;
+  }
+
+  add(item) {
+    const newItem = new Node();
+
+    if (this.isEmpty()) {
+      this._first = newItem;
+      this._first.item = item;
+    } else {
+      const oldFirst = this._first;
+
+      this._first = newItem;
+      this._first.item = item;
+      this._first.next = oldFirst;
+    }
+
+    this._n = this._n + 1;
+  }
+
+  isEmpty() {
+    return this._n === 0;
+  }
+
+  size() {
+    return this._n;
+  }
+
+  [Symbol.iterator]() {
+    let cur = this._first;
+
+    return {
+      next() {
+        if (cur) {
+          const value = cur.item;
+
+          cur = cur.next;
+
+          return { done: false, value };
+        }
+
+        return { done: true };
+      }
+    };
+  }
 }
 
 test('백은 비어있는 상태로 생성된다', () => {

problem-1-2/problem-1-2.test.js

@@ -1,4 +1,75 @@
+class Node {
+  item;
+  next;
+}
+
+class Bag {
+  _n;
+  _first;
+  _sum;
+
+  constructor() {
+    this._n = 0;
+    this._sum = 0;
+  }
+
+  add(item) {
+    const newItem = new Node();
+
+    if (this.isEmpty()) {
+      this._first = newItem;
+      this._first.item = item;
+    } else {
+      const oldFirst = this._first;
+
+      this._first = newItem;
+      this._first.item = item;
+      this._first.next = oldFirst;
+    }
+
+    this._n = this._n + 1;
+  }
+
+  isEmpty() {
+    return this._n === 0;
+  }
+
+  size() {
+    return this._n;
+  }
+
+  [Symbol.iterator]() {
+    let cur = this._first;
+
+    return {
+      next() {
+        if (cur) {
+          const value = cur.item;
+
+          cur = cur.next;
+
+          return { done: false, value };
+        }
+
+        return { done: true };
+      }
+    };
+  }
+}
+
 const solution = (numbers) => {
+  const bag = new Bag();
+
+  for (const num of numbers) {
+    bag.add(num);
+  }
+
+  let sum = 0;
+  for (const item of bag) {
+    sum += item;
+  }
+
+  return Math.floor(sum / bag.size());
 };
 
 test('숫자 배열의 평균을 반환한다', () => {

problem-2-1/problem-2-1.test.js

@@ -1,4 +1,76 @@
+class Node {
+  item;
+  next;
+}
+
 class Stack {
+  _n;
+  _first;
+
+  constructor() {
+    this._n = 0;
+  }
+
+  push(item) {
+    const newItem = new Node();
+
+    if (this.isEmpty()) {
+      this._first = newItem;
+      this._first.item = item;
+    } else {
+      const oldFirst = this._first;
+
+      this._first = newItem;
+      this._first.item = item;
+      this._first.next = oldFirst;
+    }
+
+    this._n = this._n + 1;
+  }
+
+  pop() {
+    if (this.isEmpty()) {
+      throw new Error('스택이 비어있습니다');
+    }
+
+    const target = this._first;
+
+    if (this._first.next) {
+      this._first = this._first.next;
+    } else {
+      this._first = undefined;
+    }
+
+    this._n = this._n - 1;
+
+    return target.item;
+  }
+
+  isEmpty() {
+    return this._n === 0;
+  }
+
+  size() {
+    return this._n;
+  }
+
+  [Symbol.iterator]() {
+    let cur = this._first;
+
+    return {
+      next() {
+        if (cur) {
+          const value = cur.item;
+
+          cur = cur.next;
+
+          return { done: false, value };
+        }
+
+        return { done: true };
+      }
+    };
+  }
 }
 
 test('스택을 생성하면 비어있다', () => {

problem-2-2/problem-2-2.test.js

@@ -1,4 +1,107 @@
+class Node {
+  item;
+  next;
+}
+
+class Stack {
+  _n;
+  _first;
+
+  constructor() {
+    this._n = 0;
+  }
+
+  push(item) {
+    const newItem = new Node();
+
+    if (this.isEmpty()) {
+      this._first = newItem;
+      this._first.item = item;
+    } else {
+      const oldFirst = this._first;
+
+      this._first = newItem;
+      this._first.item = item;
+      this._first.next = oldFirst;
+    }
+
+    this._n = this._n + 1;
+  }
+
+  pop() {
+    if (this.isEmpty()) {
+      throw new Error('스택이 비어있습니다');
+    }
+
+    const target = this._first;
+
+    if (this._first.next) {
+      this._first = this._first.next;
+    } else {
+      this._first = undefined;
+    }
+
+    this._n = this._n - 1;
+
+    return target.item;
+  }
+
+  isEmpty() {
+    return this._n === 0;
+  }
+
+  size() {
+    return this._n;
+  }
+
+  [Symbol.iterator]() {
+    let cur = this._first;
+
+    return {
+      next() {
+        if (cur) {
+          const value = cur.item;
+
+          cur = cur.next;
+
+          return { done: false, value };
+        }
+
+        return { done: true };
+      }
+    };
+  }
+}
+
 const solution = (string) => {
+  const stack = new Stack();
+
+  const open = ['{', '(', '[']; // open 일때 push
+  const pair = { // close 일때 pop
+    '}': '{',
+    ')': '(',
+    ']': '[',
+  };
+
+  for (const str of string) {
+    const isOpenBracket = open.includes(str);
+
+    if (isOpenBracket) {
+      stack.push(str);
+    } else {
+      try {
+        const popped = stack.pop();
+
+        if (!pair[str] === popped) {
+          return false;
+        }
+      } catch(e) {
+        return false;
+      }
+    }
+  }
+
+  return true;
 };
 
 test('문자열에 포함된 괄호의 짝이 맞을 때 true를 반환한다', () => {