import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Arrays;

public class Search {

  /**
   * Make an array of random elements
   * @param N Size of the desired array
   * @return Array of size N of random elements from [0, N)
   */
  public static int[] makeArray(int N) {
    int[] arr = new int[N];
    for(int i = 0; i < N; ++i) {
      arr[i] = (int)(Math.random()*N);
    }
    return arr;
  }

  /**
   * Make a sorted array of random elements
   * @param N Size of the desired array
   * @return Sorted array of size N of random elements from [0, N)
   */
  public static int[] makeSortedArray(int N) {
    int[] arr = new int[N];
    for(int i = 0; i < N; ++i) {
      arr[i] = (int)(Math.random()*N);
    }
    Arrays.sort(arr);
    return arr;
  }

  /**
   * Linear search an array for a key
   * @param arr Array
   * @param key Key
   * @return true if arr contains key, false otherwise
   */
  public static boolean linearSearch(int[] arr, int key) {
    for(int i = 0; i < arr.length; ++i)
      if(arr[i] == key)
        return true;
    return false;
  }

  /**
   * Binary search a sorted array for a key
   * @param arr Array
   * @param key Key
   * @return true if arr contains key, false otherwise
   */
  public static boolean binarySearch(int[] arr, int key) {
    int low = 0;
    int high = arr.length - 1;
    while(low <= high) {
      int mid = (low + high)/2;
      if(key < arr[mid])       high = mid - 1;
      else if(key > arr[mid])  low = mid + 1;
      else /*key == arr[mid]*/ return true;
    }
    return false;
  }

  public static void main(String[] args) throws FileNotFoundException {
    PrintWriter pw = new PrintWriter("data_search.csv");
    System.out.printf("%8s%15s%15s\n", "N", "Linear Search", "Binary Search");
    pw.println("N,Linear Search,Binary Search");

    int maxSize = 2000000;
    for(int N = 2; N < maxSize; N*=2) {
      //Determine repetitions for algorithm
      int repetitions = Math.max(10, maxSize/N);

      //Output N
      System.out.printf("%8d", N);
      pw.print(N);

      //Make an array
      int[] arr = makeArray(N);

      //Time linear search
      long startLS = System.nanoTime();

      for(int k = 0; k < repetitions; ++k) {
        int key = (int)(Math.random() * N);
        linearSearch(arr, key);
      }

      long stopLS = System.nanoTime();
      double durationLS = (stopLS - startLS)/1e9/repetitions;

      System.out.printf("%15.5e", durationLS);
      pw.print("," + durationLS);

      //Time binary search
      long startBS = System.nanoTime();

      for(int k = 0; k < repetitions; ++k) {
        int key = (int)(Math.random() * N);
        binarySearch(arr, key);
      }

      long stopBS = System.nanoTime();
      double durationBS = (stopBS - startBS)/1e9/repetitions;

      System.out.printf("%15.5e", durationBS);
      pw.print("," + durationBS);

      //Finish the line
      System.out.println();
      pw.println();
    }

    pw.flush();
    pw.close();
  }
}