Completed lesson07 exercises: implemented compareStrings, computeFactorial, getFirstNFibonacciNumbers, binarySearch, and other conditional functions

Author: thusser252

lesson_07/conditionals/src/lesson7.ts

@@ -12,9 +12,13 @@ export function compareStrings(a: string, b: string): number {
   // if it is greater, and 0 if the strings are equal.
   const distance = computeLexicographicDistance(a, b);
 
-  // TODO(you): Finish this method.
-
-  return 0;
+  if (distance < 0) {
+    return -1;
+  } else if (distance > 0) {
+    return 1;
+  } else {
+    return 0;
+  }
 }
 
 /**
@@ -24,7 +28,10 @@ export function compareStrings(a: string, b: string): number {
  * @return The factorial of n.
  */
 export function computeFactorial(n: number): number {
-  return 0;
+  if (n <= 1) {
+    return 1;
+  }
+  return n * computeFactorial(n - 1);
 }
 
 /**
@@ -34,7 +41,21 @@ export function computeFactorial(n: number): number {
  * @return An array containing the first `n` Fibonacci values.
  */
 export function getFirstNFibonacciNumbers(n: number): number[] {
-  return [];
+  if (n <= 0) {
+    return [];
+  }
+
+  const fibonacci: number[] = [1];
+  if (n === 1) {
+    return fibonacci;
+  }
+
+  fibonacci.push(1);
+  for (let i = 2; i < n; i++) {
+    fibonacci.push(fibonacci[i - 1] + fibonacci[i - 2]);
+  }
+
+  return fibonacci;
 }
 
 /**
@@ -59,11 +80,11 @@ export function binarySearch(
 
   const pivotIndex = Math.floor((start + end) / 2); // The index in the middle of the array.
 
-  // TODO(you): Finish implementing this algorithm
-
-  // If values[pivotIndex] is equal to value then return `pivotIndex`.
-  // Else if values[pivotIndex] is greater than the value, then
-  // call `binarySearch(values, start, pivotIndex - 1, value)` and return its value;
-  // Else call `binarySearch(values, pivotIndex + 1, end, value)` and return its value.
-  return -1;
+  if (values[pivotIndex] === value) {
+    return pivotIndex;
+  } else if (values[pivotIndex] > value) {
+    return binarySearch(values, start, pivotIndex - 1, value);
+  } else {
+    return binarySearch(values, pivotIndex + 1, end, value);
+  }
 }

lesson_07/conditionals/src/part_c.ts

@@ -3,20 +3,64 @@
  * and at least one uppercase letter and one digit.
  *
  * @param password
- * @returns
+ * @returns true if strong, false otherwise
  */
 export function isStrongPassword(password: string): boolean {
-  return false;
+  // Check length
+  if (password.length < 8) {
+    return false;
+  }
+
+  let hasUppercase = false;
+  let hasDigit = false;
+
+  // Check for uppercase and digits in one pass through the string
+  for (let i = 0; i < password.length; i++) {
+    const ch = password[i];
+
+    // Check uppercase
+    if (ch >= "A" && ch <= "Z") {
+      hasUppercase = true;
+    }
+
+    // Check digit
+    if (ch >= "0" && ch <= "9") {
+      hasDigit = true;
+    }
+  }
+
+  // Strong only if all conditions are met
+  if (hasUppercase && hasDigit) {
+    return true;
+  } else {
+    return false;
+  }
 }
 
 /**
  * Determines the day of the week on the given 0-based number.
  *
  * @param day
- * @returns
+ * @returns The day name or "Invalid day" if out of range.
  */
 export function getDayOfWeek(day: number): string {
-  return "";
+  if (day === 0) {
+    return "Sunday";
+  } else if (day === 1) {
+    return "Monday";
+  } else if (day === 2) {
+    return "Tuesday";
+  } else if (day === 3) {
+    return "Wednesday";
+  } else if (day === 4) {
+    return "Thursday";
+  } else if (day === 5) {
+    return "Friday";
+  } else if (day === 6) {
+    return "Saturday";
+  } else {
+    return "";
+  }
 }
 
 /**
@@ -28,8 +72,18 @@ export function getDayOfWeek(day: number): string {
  * - Seniors 60 years old and older pay 15 dollars.
  *
  * @param age
- * @returns
+ * @returns Ticket price in dollars.
  */
 export function getTicketPrice(age: number): number {
-  return 0;
+  if (age < 5) {
+    return 0;
+  } else if (age >= 5 && age <= 17) {
+    return 10;
+  } else if (age >= 18 && age <= 59) {
+    return 20;
+  } else if (age >= 60) {
+    return 15;
+  } else {
+    return 0;
+  }
 }