feat: adds David Smith Lesson07

lesson_07/conditionals/src/lesson7.ts

@@ -7,24 +7,30 @@ import { computeLexicographicDistance } from "./util.js";
  * @return True if the age corresponds to a voting age and false otherwise.
  */
 export function canVote(age: number): boolean {
-  return false;
+  if (age >= 18) {
+    return true;
+  } else return false;
 }
 
 /**
  * Compares two strings lexicographically.
  *
- * @param a The first `string` to compare.
- * @param b The second `string` to compare.
+ * @param a The first string to compare.
+ * @param b The second string to compare.
  * @return -1 if a is less than b, 1 if a is greater than b, and 0 otherwise.
  */
 export function compareStrings(a: string, b: string): number {
-  // The distance will be a number less than 0 if string `a` is lexicographically less than `b`, 1
-  // if it is greater, and 0 if the strings are equal.
+  // The distance will be a number less than 0 if string a is lexicographically less than b,
+  // greater than 0 if a 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;
+  }
 }
 
 /**
@@ -37,7 +43,27 @@ export function compareStrings(a: string, b: string): number {
  * @return The letter grade ("A+", "A", "A-", "B+", etc.).
  */
 export function convertGpaToLetterGrade(gpa: number): string {
-  return "F";
+  if (gpa === 4) {
+    return "A";
+  } else if (gpa >= 3.7) {
+    return "A-";
+  } else if (gpa >= 3.3) {
+    return "B+";
+  } else if (gpa >= 3.0) {
+    return "B";
+  } else if (gpa >= 2.7) {
+    return "B-";
+  } else if (gpa >= 2.3) {
+    return "C+";
+  } else if (gpa >= 2.0) {
+    return "C";
+  } else if (gpa >= 1.7) {
+    return "C-";
+  } else if (gpa >= 1.3) {
+    return "D+";
+  } else if (gpa >= 1.0) {
+    return "D";
+  } else return "F";
 }
 
 /**
@@ -47,7 +73,10 @@ export function convertGpaToLetterGrade(gpa: number): string {
  * @return The factorial of n.
  */
 export function computeFactorial(n: number): number {
-  return 0;
+  if (n < 0) {
+    throw new Error("Negative numbers are invalid.");
+  }
+  return n <= 1 ? 1 : n * computeFactorial(n - 1);
 }
 
 /**
@@ -57,17 +86,27 @@ export function computeFactorial(n: number): number {
  * @return The sum of all the values.
  */
 export function addNumbers(values: number[]): number {
-  return 0;
+  return values.reduce((sum, current) => sum + current, 0);
 }
 
 /**
  * Returns an array of the first `n` Fibonacci numbers starting from 1.
  *
- * @param n The first `n` of Fibonacci values to compute.
+ * @param n The first `n` Fibonacci values to compute.
  * @return An array containing the first `n` Fibonacci values.
  */
 export function getFirstNFibonacciNumbers(n: number): number[] {
-  return [];
+  if (n <= 0) return [];
+  if (n === 1) return [1];
+
+  const fibonacci: number[] = [1, 1];
+
+  for (let i = 2; i < n; i++) {
+    const nextFibonacci = fibonacci[i - 1] + fibonacci[i - 2];
+    fibonacci.push(nextFibonacci);
+  }
+
+  return fibonacci;
 }
 
 /**
@@ -90,13 +129,12 @@ export function binarySearch(
     return -1;
   }
 
-  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;
+  const pivotIndex = Math.floor((start + end) / 2);
+  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);
+  }
 }