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Rajivv91Rajivv91
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algorithms
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‎Count_sort.java

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import java.util.*;
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public class Count_sort {
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public static void main(String[] args){
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Random r = new Random();
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int size=0; //Initializing size of the array
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int no_of_runs=0; // for the number of runs
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try {
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//reading the size of array
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Scanner scan_array_size = new Scanner(System.in); // scanner for array size
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Scanner scan_runs = new Scanner(System.in); //scanner for number of runs
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System.out.println("Enter the number of elements to sort(using count sort):");
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size = scan_array_size.nextInt();
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System.out.println("\n how many times you want to run the algorithm??");
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no_of_runs = scan_runs.nextInt();
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//int[] average = new int[size];
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float average=0;
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// print the array before sorting
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/*System.out.println("before sorting");
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PrintArray(random_integers);*/
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for (int x = 1; x <= no_of_runs; x++) {
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//generating random numbers
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int[] random_integers = new int[size];
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for (int i = 0; i < random_integers.length; i++) {
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random_integers[i] = r.nextInt(3000000);
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}
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// count sort start
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long start = System.currentTimeMillis(); // starting timer
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int low = 0;
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int high = random_integers.length - 1;
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countSort(random_integers);
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long time = System.currentTimeMillis() - start; //ending timer
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// count sort end
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// print the array after sorting
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/*System.out.println("after sorting");
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PrintArray(random_integers);*/
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System.out.println("run "+ x +" time taken:" + time + " milli second");
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//average[x]=(int)time;
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average+=(float)time;
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} // end of for loop for number of runs
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System.out.println("\n average time taken:"+average/no_of_runs+ " milli second" );
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} // end of try
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catch (Exception e) {
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System.out.println("\n Invalid Input");
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e.printStackTrace();
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} // end of catch
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} // end of main
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// count sort algorithm
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private static void countSort(int[] arr) {
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int N = arr.length;
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if (N == 0)
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return;
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/** find max and min values **/
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int max = arr[0], min = arr[0];
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for (int i = 1; i < N; i++)
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{
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if (arr[i] > max)
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max = arr[i];
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if (arr[i] < min)
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min = arr[i];
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}
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//int MAX_RANGE = 1000000;
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int range = max - min + 1;
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int[] count = new int[range];
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/** make count/frequency array for each element **/
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for (int i = 0; i < N; i++)
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count[arr[i] - min]++;
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/** modify count so that positions in final array is obtained **/
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for (int i = 1; i < range; i++)
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count[i] += count[i - 1];
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/** modify original array **/
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int j = 0;
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for (int i = 0; i < range; i++)
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while (j < count[i])
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arr[j++] = i + min;
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}
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// this function prints the array
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private static void PrintArray(int[] random_integers) {
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for (int i = 0; i < random_integers.length; i++)
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{System.out.println(random_integers[i]);}
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}
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} // end of count sort

‎MedianFinding.java

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import java.util.Random;
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import java.util.Scanner;
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public class Median_Finding {
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public static void main(String[] args){
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Random high = new Random();
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int size=0; //Initializing size of the array
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int no_of_runs=0; // for the number of runs
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int kth_smallest=0; // kth smallest element
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try {
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//reading the size of array
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Scanner scan_array_size = new Scanner(System.in); // scanner for array size
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Scanner scan_runs = new Scanner(System.in); //scanner for number of runs
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Scanner scan_ith_smallest = new Scanner(System.in); // scanner for array size
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System.out.println("Enter the number of elements to sort (using quick sort):");
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size = scan_array_size.nextInt();
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System.out.println("\nsize how many times you want to run the algorithm??");
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no_of_runs = scan_runs.nextInt();
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System.out.println("\nsize Please enter the ith smallest element you want to find");
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kth_smallest = scan_ith_smallest.nextInt();
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float average=0;
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for (int x = 1; x <= no_of_runs; x++) {
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//generating random numbers
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int[] random_integers = new int[size];
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random_integers[0] = high.nextInt(500000);
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for(int nextNumber = 1; nextNumber < random_integers.length; ++nextNumber) {
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random_integers[nextNumber] = high.nextInt(20);
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for( int testNumber = 0; testNumber < nextNumber; ++testNumber ) {
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if( random_integers[testNumber] == random_integers[nextNumber] ) {
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random_integers[nextNumber] = high.nextInt(500000);
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testNumber = 0;
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}
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}// end of for, test number
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}// end of for, next number
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/**
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// print the array before sorting
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System.out.println("before sorting");
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PrintArray(random_integers);
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*/
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int low = 0;
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int high1 = random_integers.length - 1;
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int smallest;
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long start = System.currentTimeMillis(); // starting timer
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smallest = kthSmallest(random_integers,low,high1,kth_smallest);
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long time = System.currentTimeMillis() - start; //ending timer
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// print the array after sorting
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System.out.println("after sorting");
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PrintArray(random_integers);
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System.out.println("\nrun "+ x +" time taken:" + time + " milli second");
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System.out.println("\nkth smallest element is:"+smallest);
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//average[x]=(int)time;
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average+=(float)time;
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} // end of for loop for number of runs
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System.out.println("\naverage time taken: "+average/no_of_runs+ " milli second" );
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} // end of try
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catch (Exception e) {
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System.out.println("\nsize Invalid Input");
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e.printStackTrace();
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} // end of catch
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} // end of main
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private static int medianFind(int[] tempArr, int size) {
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int i,j,min,temp;
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for ( i = 0; i < tempArr.length; i++){
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min=i;
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for(j=i+1; j < tempArr.length; j++){
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if(tempArr[j]<tempArr[min])
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min=j;
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}
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// now swap the elements
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temp=tempArr[min];
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tempArr[min]=tempArr[i];
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tempArr[i]=temp;
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}
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return tempArr[size/2];
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}// end of medianFind
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public static int kthSmallest(int[] arr, int low, int high, int k){
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if (k > 0 && k <= high-low+1){
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int size = high-low+1;
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int i;
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int [] median = new int[(size+4)/5];
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int [] temp = new int[5];
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for (i=0; i<size/5; i++){
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for (int j=0; j<5; j++)
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temp[j] = arr[i*5+j];
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median[i] = medianFind(temp, 5);
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}
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if (i*5 < size) //For last group with less than 5 elements
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{
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for (int j=0; j < (i*5)%size; j++)
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temp[j] = arr[i*5+j];
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median[i] = medianFind(temp, (i*5)%size);
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i++;
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}
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int pivot;
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if (i==1)
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pivot = median[i-1];
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else
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pivot = kthSmallest(median, 0, i-1, i/2);
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// Partition the array around a random element and
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// get position of pivot element in sorted array
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int pos = partition(arr, low, high, pivot);
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// If position is same as k
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if (pos-low == k-1)
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return arr[pos];
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if (pos-low > k-1) // If position is more, recur for left
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return kthSmallest(arr, low, pos-1, k);
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// Else recur for right subarray
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return kthSmallest(arr, pos+1, high, k-pos+low-1);
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}
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// If k is more than number of elements in array
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return 9999999;
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}// end of method ith smallest
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static int partition(int arr[], int low, int high, int x)
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{
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// Search for x in arr[low..high] and move it to end
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int i;
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for (i=low; i<high; i++)
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if (arr[i] == x)
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break;
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swap(arr, i, high);
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// Standard partition algorithm
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i = low;
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for (int j = low; j <= high - 1; j++)
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{
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if (arr[j] <= x)
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{
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swap(arr, i, j);
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i++;
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}
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}
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swap(arr, i, high);
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return i;
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}
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private static void swap (int [] arr, int i, int j){
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int temp = arr[i];
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arr [i] = arr [j];
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arr[j] = temp;
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}
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// this function prints the array
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private static void PrintArray(int[] random_integers) {
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for (int i = 0; i < random_integers.length; i++)
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{System.out.println(random_integers[i]);}
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}
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}//end of class
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