week2-01 hard problems

01-js/.gitignore

@@ -0,0 +1 @@
+node_modules

01-js/easy/anagram.js

@@ -5,7 +5,20 @@
 */
 
 function isAnagram(str1, str2) {
-
+  if( str1.length !== str2.length ) return false;
+  str1 = str1.toLowerCase();
+  str2 = str2.toLowerCase();
+  const freq = new Array(256).fill(0);
+  for(let i = 0 ; i < str1.length ; i++){
+    freq[str1[i].charCodeAt(0)]++; 
+  }
+  for(let letter of str2){
+    freq[letter.charCodeAt(0)]--;
+  }
+  for(let i = 0 ; i < 256; i++){
+    if(freq[i] !== 0)return false;
+  }
+  return true;
 }
 
 module.exports = isAnagram;

01-js/easy/expenditure-analysis.js

@@ -14,7 +14,26 @@
 */
 
 function calculateTotalSpentByCategory(transactions) {
-  return [];
+  const mp = {};
+  for(let i = 0 ; i < transactions.length; i++){
+    const currentTransaction = transactions[i];
+    const category = currentTransaction.category;
+    const price = currentTransaction.price;
+    if(!mp[category]){
+      mp[category] = price;
+    }
+    else{
+      mp[category] += price;
+    }
+  }
+  return Object.entries(mp).map(category => {
+    const [categoryName , totalMoneySpent] = category;
+    return {
+      category: categoryName,
+      totalSpent: totalMoneySpent,
+    }
+  })
+  // return [];
 }
 
 module.exports = calculateTotalSpentByCategory;

01-js/easy/findLargestElement.js

@@ -6,7 +6,11 @@
 */
 
 function findLargestElement(numbers) {
-
+    let largestElement = numbers[0];
+    for(const num of numbers){
+        if(num > largestElement)largestElement = num;
+    }
+    return largestElement;
 }
 
 module.exports = findLargestElement;

01-js/hard/todo-list.js

@@ -11,7 +11,31 @@
 */
 
 class Todo {
-
+  todos = [];
+  isInvalidIndexToOperate(index) {
+    return index < 0 || index >= this.todos.length;
+  }
+  add(task) {
+    this.todos.push(task);
+  }
+  remove(index) {
+    if (this.isInvalidIndexToOperate(index)) return;
+    this.todos.splice(index, 1);
+  }
+  update(index, updatedTodo) {
+    if (this.isInvalidIndexToOperate(index)) return;
+    this.todos[index] = updatedTodo;
+  }
+  getAll() {
+    return this.todos;
+  }
+  get(indexOfTodo) {
+    if (this.isInvalidIndexToOperate(indexOfTodo)) return null;
+    return this.todos[indexOfTodo];
+  }
+  clear() {
+    this.todos = [];
+  }
 }
 
 module.exports = Todo;

01-js/medium/countVowels.js

@@ -6,7 +6,15 @@
 */
 
 function countVowels(str) {
-    // Your code here
+    const isVowel = (letter) => {
+      const lowerCased = letter.toLowerCase();
+      return lowerCased === 'a' || lowerCased === 'e' || lowerCased === 'i' || lowerCased === 'o' || lowerCased === 'u'
+    }
+    let vowelCount = 0;
+    for(const char of str){
+      if(isVowel(char))vowelCount++;
+    }
+    return vowelCount;
 }
 
 module.exports = countVowels;

01-js/medium/palindrome.js

@@ -4,6 +4,23 @@
 */
 
 function isPalindrome(str) {
+  let newStr = "";
+  str = str.toLowerCase();
+  for (const char of str) {
+    if (
+      char.charCodeAt(0) >= "a".charCodeAt(0) &&
+      char.charCodeAt(0) <= "z".charCodeAt(0)
+    )
+      newStr += char;
+  }
+
+  let start = 0,
+    end = newStr.length - 1;
+  while (start < end) {
+    if (newStr[start] !== newStr[end]) return false;
+    start++;
+    end--;
+  }
   return true;
 }
 

01-js/medium/times.js

@@ -9,5 +9,14 @@ There is no automated test for this one, this is more for you to understand time
 */
 
 function calculateTime(n) {
-    return 0.01;
-}
+  const start = Date.now();
+  for (let i = 1; i <= n; i++);
+  const end = Date.now();
+  const time_elapsed = (end - start) ;
+  return time_elapsed;
+}
+
+const time1 = calculateTime(100);
+const time2 = calculateTime(100000);
+const time3 = calculateTime(1000000000);
+console.log(time1, time2, time3);