100xdevs Cohort 2 Week 1 to Week 4 assignments

01-js/easy/anagram.js

@@ -5,7 +5,27 @@
 */
 
 function isAnagram(str1, str2) {
+  if (str1.length != str2.length) {
+    return false;
+  }
+  str1 = str1.toLowerCase();
+  str2 = str2.toLowerCase();
+  let charcount = 256;
+  let count = new Array(charcount);
+  for (let i = 0; i < charcount; i++){
+    count[i] = 0;
+  }
+  for (let i = 0; i < str1.length; i++) {
+    count[str1[i].charCodeAt(0)]++;
+    count[str2[i].charCodeAt(0)]--;
+  }
 
+  for (let i = 0; i < charcount; i++) {
+    if (count[i] != 0) {
+      return false;
+    }
+  }
+  return true;
 }
 
 module.exports = isAnagram;

01-js/easy/expenditure-analysis.js

@@ -14,7 +14,22 @@
 */
 
 function calculateTotalSpentByCategory(transactions) {
-  return [];
+  let categoryMap = new Map();
+  transactions.forEach(item => {
+     if (categoryMap.has(item.category)){
+       categoryMap.set(item.category, categoryMap.get(item.category)+item.price);
+     } else {
+       categoryMap.set(item.category, item.price);
+     }
+  });
+
+  const result = [];
+  categoryMap.forEach((totalSpent,category) => {
+   result.push({"category" : category, "totalSpent" : totalSpent})
+  });
+  return result;
 }
 
+
+
 module.exports = calculateTotalSpentByCategory;

01-js/easy/findLargestElement.js

@@ -6,7 +6,16 @@
 */
 
 function findLargestElement(numbers) {
+
+    let max = numbers[0];
+    for (let i = 1; i < numbers.length; i++) {
+        if (numbers[i] > max) {
+            max = numbers[i];
+        }
+    }
+    return max;
 
 }
 
-module.exports = findLargestElement;
+module.exports = findLargestElement;
+

01-js/hard/calculator.js

@@ -16,6 +16,54 @@
   Once you've implemented the logic, test your code by running
 */
 
-class Calculator {}
+class Calculator {
+  constructor() {
+    this.result = 0;
+  }
+  add(number) {
+    this.result += number;
+  }
+  subtract(number) {
+    this.result -= number;
+  }
+  multiply(number) {
+    this.result *= number;
+  }
+  divide(number) {
+    if (number == 0){
+      throw new Error("Can't divide by zero");
+    }
+    this.result = this.result/number;
+  }
+  clear() {
+    this.result = 0;
+  }
+  getResult(){
+    return this.result;
+  }
+  calculate(expression) {
+    const temp = expression;
+    const cleanedExpression = temp.replace(/\s+/g, ''); // s+ matches one or more white spaces g is for matching global search replacing all occurence
+    const validExpression = /^[0-9+\-*/().]+$/.test(cleanedExpression); //regular expression to check if it contains only valid character for mathematical expression
+
+    if (!validExpression) {
+        throw new Error("Invalid expression"); //throw error for expression like 5 + abc
+    }
+
+    try {
+        this.result = eval(expression);
+    } catch (err) {
+        throw new Error("Invalid expression")
+    }
+    if (this.result === Infinity) {
+      //when trying to divide by zero eval result in Infinity to throw error for divide by 0 adding this check here
+        throw new Error("Cannot divide a number by 0")
+    }
+    return this.result;
+  }
+
+
+}
+
 
 module.exports = Calculator;

01-js/hard/todo-list.js

@@ -11,7 +11,39 @@
 */
 
 class Todo {
-
+    constructor() {
+      this.todos = [];
+    }
+    add(todo) {
+      this.todos.push(todo);
+    }
+    remove(indexOfTodo) {
+      if (indexOfTodo >= 0 && indexOfTodo < this.todos.length){
+        this.todos.splice(indexOfTodo,1);
+      } else {
+        console.error("Invalid , Error in Remove, cnat remove");
+      }
+    }
+    update(index,updatedTodo){
+      if (index >= 0 && index < this.todos.length){
+        this.todos[index] = updatedTodo;
+      } else {
+        console.error("Invalid , Error in update, cnat update");
+      }
+    }
+    getAll(){
+      return this.todos;
+    }
+    get(indexOfTodo) {
+      if (indexOfTodo >= 0 && indexOfTodo < this.todos.length){ 
+        return this.todos[indexOfTodo];
+      } else {
+        return null;
+      }
+    }
+    clear(){
+      this.todos=[];
+    }
 }
 
 module.exports = Todo;

01-js/medium/countVowels.js

@@ -6,7 +6,17 @@
 */
 
 function countVowels(str) {
-    // Your code here
+  // Your code here
+  str = str.toLowerCase();
+  const vowels = new Set(['a', 'e', 'i', 'o', 'u']);
+
+  let count = 0;
+  for (let i = 0; i < str.length; i++) {
+    if (vowels.has(str.charAt(i))) {
+      count++;
+    }
+  }
+  return count;
 }
 
 module.exports = countVowels;

01-js/medium/palindrome.js

@@ -4,6 +4,17 @@
 */
 
 function isPalindrome(str) {
+  str = str.toLowerCase().replace(/[^a-z0-9]/g, '');
+  let left = 0;
+  let right = str.length-1;
+  while (left < right){
+    if (str[left] != str[right]){
+      return false;
+    } else {
+      left ++;
+      right --;
+    }
+  }
   return true;
 }
 

01-js/medium/times.js

@@ -9,5 +9,15 @@ There is no automated test for this one, this is more for you to understand time
 */
 
 function calculateTime(n) {
-    return 0.01;
-}
+    const st = new Date();
+    let sum = 0;
+    for (let i = 0 ; i <= n; i++) {
+        sum += i;
+    }
+    const en = new Date();
+    return en-st;
+}
+
+console.log(calculateTime(100));
+console.log(calculateTime(100000));
+console.log(calculateTime(1000000000));

week-2/01-async-js/easy/1-counter.js

@@ -0,0 +1,20 @@
+/*
+## Create a counter in JavaScript
+
+We have already covered this in the second lesson, but as an easy recap try to code a counter in Javascript
+It should go up as time goes by in intervals of 1 second
+*/
+function counter() {
+  let count = 30;
+  console.log(count);
+  const interval = setInterval(() =>{
+    count--;
+    console.log(count);
+    if (count == 0){
+        clearInterval(interval);
+        console.log("CountDown Finished");
+    }
+  },1000);
+
+}
+counter();

week-2/01-async-js/easy/2-counter.js

@@ -0,0 +1,18 @@
+/*
+## Counter without setInterval
+
+Without using setInterval, try to code a counter in Javascript.
+*/
+let count = 30;
+function counter() {
+
+    if (count > 0) {
+        console.log(count);
+        count--;
+        setTimeout(counter,1000);
+    } else {
+        console.log("count down finished !!!");
+    }
+}
+
+counter();

week-2/01-async-js/easy/3-read-from-file.js

@@ -0,0 +1,29 @@
+/*
+Write code to read contents of a file and print it to the console. 
+You can use the fs library to as a black box, the goal is to understand async tasks. 
+Try to do an expensive operation below the file read and see how it affects the output. 
+Make the expensive operation more and more expensive and see how it affects the output. 
+*/
+const fs = require('fs');
+console.log("read from file");
+let filePath = "./3-read-from-file.md";
+fs.readFile(filePath,'utf-8',(err,data) => {
+    if (err) {
+        console.log(err);
+    } else {
+        console.log("data in the file is ");
+        console.log(data);
+    }
+});
+
+console.log("calc sum");
+
+let sum = 0;
+let n = 100000000;
+ for (let i = 0; i < n; i++) {
+    sum += i;
+ }
+ console.log(sum);
+ console.log("everything done");
+
+

week-2/01-async-js/easy/4-write-to-file.js

@@ -0,0 +1,18 @@
+/*
+## Write to a file
+Using the fs library again, try to write to the contents of a file.
+You can use the fs library to as a black box, the goal is to understand async tasks.
+*/
+const fs = require('fs');
+
+let data =" The file is written using fs write";
+let filePath = './4-write-to-file.md';
+fs.writeFile(filePath, data, (err,success) =>{
+    if (err) {
+        console.log(err);
+    } else {
+        console.log(success);
+        console.log("written");
+    }
+});
+console.log("writing");

week-2/01-async-js/hard (promises)/1-promisify-setTimeout.js

@@ -2,7 +2,14 @@
     Write a function that returns a promise that resolves after n seconds have passed, where n is passed as an argument to the function.
 */
 
+
 function wait(n) {
+    let p = new Promise(function(resolve){
+        setTimeout(resolve,n*1000);
+    });
+    return p;
 }
 
+
+
 module.exports = wait;

week-2/01-async-js/hard (promises)/2-sleep-completely.js

@@ -5,6 +5,12 @@
  */
 
 function sleep(milliseconds) {
+    let p = new Promise(function(resolve){
+        setTimeout(resolve,milliseconds);
+    });
+    return p;
+
+
 }
 
 module.exports = sleep;

week-2/01-async-js/hard (promises)/3-promise-all.js

@@ -5,19 +5,30 @@
  */
 
 function wait1(t) {
-
+  return new Promise(function(resolve){
+    setTimeout(resolve,t*1000);
+  });
 }
 
 function wait2(t) {
-
+    return new Promise(function(resolve){
+        setTimeout(resolve,t*1000);
+      })
 }
 
 function wait3(t) {
-
+    return new Promise(function(resolve){
+        setTimeout(resolve,t*1000);
+      })
 }
 
 function calculateTime(t1, t2, t3) {
+    const start = Date.now();
+    return Promise.all([wait1(t1,),wait2(t2),wait3(t3)]).then(function(){
+        const end = Date.now();
+        return end-start;
 
+    });
 }
 
 module.exports = calculateTime;