Update solutions

Author: Sven97

src/Chapter07/Exercise0716_Execution_time.java

@@ -0,0 +1,83 @@
+/**
+ * (Execution time) Write a program that creates an array of numbers from 1 to
+ * 100,000,000 in ascending order. Display the execution time of invoking the
+ * linearSearch method and the binarySearch method in Listings 7.6 and
+ * 7.7 respectively. Display the execution time of invoking both searches for the following
+ * numbers: 1; 25,000,000; 50,000,000; 75,000,000; 100,000,000. You can
+ * use the following code template to obtain the execution time:
+ * long startTime = System.nanoTime();
+ * perform the task;
+ * long endTime = System.nanoTime();
+ * long executionTime = endTime − startTime;
+ *
+ * Created by Sven on 08/20/19.
+ */
+package Chapter07;
+
+public class Exercise0716_Execution_time {
+    public static void main(String[] args) {
+        int[] list = new int[100000000];
+        for (int i = 1; i < 100000000; i++) {
+            list[i] = i;
+        }
+
+        long startTime, endTime, executionTime;
+        int[] searchNum = {1, 25000000, 50000000, 75000000, 100000000};
+        long[] linearSearchTime = new long[searchNum.length];
+        long[] binarySearchTime = new long[searchNum.length];
+        for (int i = 0; i < searchNum.length; i++) {
+            // linear search
+            startTime = System.nanoTime();
+            linearSearch(list, searchNum[i]);
+            endTime = System.nanoTime();
+            executionTime = endTime - startTime;
+            linearSearchTime[i] = executionTime;
+
+            // binary search
+            startTime = System.nanoTime();
+            binarySearch(list, searchNum[i]);
+            endTime = System.nanoTime();
+            executionTime = endTime - startTime;
+            binarySearchTime[i] = executionTime;
+        }
+
+        System.out.println("Search Number  |  Linear Search  |  Binary Search");
+        System.out.println("-------------------------------------------------");
+        for (int i = 0; i < searchNum.length; i++) {
+            System.out.printf("%-13d  |  %-13d  |  %-13d\n", searchNum[i], linearSearchTime[i], binarySearchTime[i]);
+        }
+    }
+
+
+    /**
+     * The method for finding a key in the list
+     */
+    public static int linearSearch(int[] list, int key) {
+        for (int i = 0; i < list.length; i++) {
+            if (key == list[i])
+                return i;
+        }
+        return -1;
+    }
+
+    /**
+     * Use binary search to find the key in the list
+     */
+    public static int binarySearch(int[] list, int key) {
+        int low = 0;
+        int high = list.length - 1;
+
+        while (high >= low) {
+            int mid = (low + high) / 2;
+            if (key < list[mid])
+                high = mid - 1;
+            else if (key == list[mid])
+                return mid;
+            else low = mid + 1;
+        }
+
+        return -low - 1; // Now high < low
+    }
+
+
+}

src/Chapter07/Exercise0717_Sort_students.java

@@ -0,0 +1,49 @@
+/**
+ * (Sort students) Write a program that prompts the user to enter the number of students,
+ * the students’ names, and their scores and prints student names in decreasing
+ * order of their scores. Assume the name is a string without spaces, use the Scanner’s
+ * next() method to read a name.
+ *
+ * Created by Sven on 08/20/19.
+ */
+package Chapter07;
+
+import java.util.Scanner;
+
+public class Exercise0717_Sort_students {
+    public static void main(String[] args) {
+        Scanner input = new Scanner(System.in);
+        System.out.print("Enter number of students: ");
+        int numOfStudents = input.nextInt();
+        String[] nameList = new String[numOfStudents];
+        double[] scoreList = new double[numOfStudents];
+
+        for (int i = 0; i < numOfStudents; i++) {
+            System.out.print("Enter student's name: ");
+            nameList[i] = input.next();
+            System.out.print("Enter " + nameList[i] + "'s score: ");
+            scoreList[i] = input.nextDouble();
+        }
+
+        // Bubble sort
+        for (int i = 0; i < numOfStudents - 1; i++) {
+            for (int j = 0; j < numOfStudents - i - 1; j++) {
+                if (scoreList[j] < scoreList[j + 1]) {
+                    // Swap scoreList[j] and scoreList[j + 1]
+                    double scoreTemp = scoreList[j];
+                    scoreList[j] = scoreList[j + 1];
+                    scoreList[j + 1] = scoreTemp;
+
+                    // Swap nameList[j] and nameList[j+1]
+                    String nameTemp = nameList[j];
+                    nameList[j] = nameList[j + 1];
+                    nameList[j + 1] = nameTemp;
+                }
+            }
+        }
+
+        for (int i = 0; i < numOfStudents; i++) {
+            System.out.printf("%-15s%-5.2f\n", nameList[i], scoreList[i]);
+        }
+    }
+}

src/Chapter07/Exercise0718_Bubble_sort.java

@@ -0,0 +1,41 @@
+/**
+ * (Sort students) Write a program that prompts the user to enter the number of students,
+ * the students’ names, and their scores and prints student names in decreasing
+ * order of their scores. Assume the name is a string without spaces, use the Scanner’s
+ * next() method to read a name.
+ *
+ * Created by Sven on 08/20/19.
+ */
+package Chapter07;
+
+import java.util.Scanner;
+
+public class Exercise0718_Bubble_sort {
+    public static void main(String[] args) {
+        Scanner input = new Scanner(System.in);
+        System.out.print("Enter 10 double numbers: ");
+        double[] numbers = new double[10];
+        for (int i = 0; i < numbers.length; i++) {
+            numbers[i] = input.nextDouble();
+        }
+        double[] sortedList = bubbleSort(numbers);
+        for (int i = 0; i < sortedList.length; i++) {
+            System.out.print(sortedList[i] + " ");
+        }
+    }
+
+    public static double[] bubbleSort(double[] list) {
+        int n = list.length;
+        for (int i = 0; i < n - 1; i++) {
+            for (int j = 0; j < n - i - 1; j++) {
+                if (list[j] > list[j + 1]) {
+                    // swap arr[j+1] and arr[i]
+                    double temp = list[j];
+                    list[j] = list[j + 1];
+                    list[j + 1] = temp;
+                }
+            }
+        }
+        return list;
+    }
+}

src/Chapter07/Exercise0719_Sorted.java

@@ -0,0 +1,41 @@
+/**
+ * (Sorted?) Write the following method that returns true if the list is already sorted
+ * in decreasing order.
+ * public static boolean isSorted(int[] list)
+ * Write a test program that prompts the user to enter a list and displays whether
+ * the list is sorted or not. Here is a sample run. Note that the first number in the
+ * input indicates the number of the elements in the list. This number is not part
+ * of the list.
+ * Enter list: 8 10 1 5 16 61 9 11 1
+ * The list is not sorted
+ * Enter list: 10 21 11 9 7 5 4 4 3 1 1
+ * The list is already sorted
+ *
+ * Created by Sven on 08/20/19.
+ */
+package Chapter07;
+
+import java.util.Scanner;
+
+public class Exercise0719_Sorted {
+    public static void main(String[] args) {
+        Scanner input = new Scanner(System.in);
+        System.out.print("Enter list: ");
+        int numberOfElements = input.nextInt();
+        int[] numbers = new int[numberOfElements];
+        for (int i = 0; i < numberOfElements; i++) {
+            numbers[i] = input.nextInt();
+        }
+
+        System.out.println(isSorted(numbers) ? "The list is already sorted" : "The list is not sorted");
+    }
+
+    public static boolean isSorted(int[] list) {
+        for (int i = 0; i < list.length - 1; i++) {
+            if (list[i] < list[i + 1]) {
+                return false;
+            }
+        }
+        return true;
+    }
+}