feat: examples from chapter 4

Author: damianobacci

chapter-4/1_bubble_sort.py

@@ -0,0 +1,12 @@
+def bubble_sort(list):
+    unsorted_until_index = len(list) - 1
+    sorted = False
+
+    while not sorted:
+        sorted = True
+        for i in range(unsorted_until_index):
+            if list[i] > list[i+1]:
+                list[i], list[i+1] = list[i+1], list[i]
+                sorted = False
+        unsorted_until_index -= 1
+    return list

chapter-4/2_quadratic_problem.ts

@@ -0,0 +1,36 @@
+function hasDuplicateValueQuadratic(array: number[]): boolean { // this function has efficiency O(N^2), because we perform an outer loop and for each element we perform an inner loop
+        let steps: number = 0
+        for (let i = 0; i < array.length; i++) {
+            for (let j = 0; j< array.length; j++) {
+                steps++
+                if (j !== j && array[i] === array[j]) {
+                    return true
+                }
+            }
+        }
+        console.log(steps)
+        return false
+}
+
+function hasDuplicateValueLinear(array: number[]): boolean { // This function has efficiency O(N), because we are only running comparisons through one loop
+    let existingNumbers: (number | undefined)[] = [] // will be something like [undefined, 1, undefined, undefined, 1], where "1" marks the if the number in that index has been seen
+    for (let i = 0; i < array.length; i++) {
+        if (existingNumbers[array[i]] === 1) {
+            return true
+        } else {
+            existingNumbers[array[i]] = 1
+        }
+    }
+    return false
+}
+
+function hasDuplicateValueSet(array: number[]): boolean { // In this case, you could also use a Set to check if a numbers has a duplicate
+    const seen = new Set<number>();
+    for (const num of array) {
+        if (seen.has(num)) {
+            return true;
+        }
+        seen.add(num);
+    }
+    return false;
+}