算法Sedgewick第四版-第1章基础-2.1Elementary Sortss-003比较算法及算法的可视化

package algorithms.elementary21;

/******************************************************************************
*  Compilation:  javac SortCompare.java
*  Execution:    java SortCompare alg1 alg2 N T
*  Dependencies: StdOut.java Stopwatch.java
*
*  Sort N random real numbers, T times using the two
*  algorithms specified on the command line.
*
*  % java SortCompare Insertion Selection 1000 100
*  For 1000 random Doubles
*    Insertion is 1.7 times faster than Selection
*
*  Note: this program is designed to compare two sorting algorithms with
*  roughly the same order of growth, e,g., insertion sort vs. selection
*  sort or mergesort vs. quicksort. Otherwise, various system effects
*  (such as just-in-time compiliation) may have a significant effect.
*  One alternative is to execute with "java -Xint", which forces the JVM
*  to use interpreted execution mode only.
*
******************************************************************************/

import java.util.Arrays;

import algorithms.analysis14.Stopwatch;
import algorithms.util.StdOut;
import algorithms.util.StdRandom;

public class SortCompare {

public static double time(String alg, Double[] a) {
Stopwatch sw = new Stopwatch();
if      (alg.equals("Insertion"))       Insertion.sort(a);
else if (alg.equals("InsertionX"))      InsertionX.sort(a);
else if (alg.equals("BinaryInsertion")) BinaryInsertion.sort(a);
else if (alg.equals("Selection"))       Selection.sort(a);
else if (alg.equals("Bubble"))          Bubble.sort(a);
else if (alg.equals("Shell"))           Shell.sort(a);
else if (alg.equals("Merge"))           Merge.sort(a);
else if (alg.equals("MergeX"))          MergeX.sort(a);
else if (alg.equals("MergeBU"))         MergeBU.sort(a);
else if (alg.equals("Quick"))           Quick.sort(a);
else if (alg.equals("Quick3way"))       Quick3way.sort(a);
else if (alg.equals("QuickX"))          QuickX.sort(a);
else if (alg.equals("Heap"))            Heap.sort(a);
else if (alg.equals("System"))          Arrays.sort(a);
else throw new IllegalArgumentException("Invalid algorithm: " + alg);
return sw.elapsedTime();
}

// Use alg to sort T random arrays of length N.
public static double timeRandomInput(String alg, int N, int T)  {
double total = 0.0;
Double[] a = new Double
;
// Perform one experiment (generate and sort an array).
for (int t = 0; t < T; t++) {
for (int i = 0; i < N; i++)
a[i] = StdRandom.uniform();
total += time(alg, a);
}
return total;
}

// Use alg to sort T random arrays of length N.
public static double timeSortedInput(String alg, int N, int T)  {
double total = 0.0;
Double[] a = new Double
;
// Perform one experiment (generate and sort an array).
for (int t = 0; t < T; t++) {
for (int i = 0; i < N; i++)
a[i] = 1.0 * i;
total += time(alg, a);
}
return total;
}

public static void main(String[] args) {
String alg1 = args[0];
String alg2 = args[1];
int N = Integer.parseInt(args[2]);
int T = Integer.parseInt(args[3]);
double time1, time2;
if (args.length == 5 && args[4].equals("sorted")) {
time1 = timeSortedInput(alg1, N, T); // Total for alg1.
time2 = timeSortedInput(alg2, N, T); // Total for alg2.
}
else {
time1 = timeRandomInput(alg1, N, T); // Total for alg1.
time2 = timeRandomInput(alg2, N, T); // Total for alg2.
}

StdOut.printf("For %d random Doubles\n    %s is", N, alg1);
StdOut.printf(" %.1f times faster than %s\n", time2/time1, alg2);
}
}

package algorithms.elementary21;

import algorithms.util.StdDraw;
import algorithms.util.StdRandom;

/******************************************************************************
*  Compilation:  javac InsertionBars.java
*  Execution:    java InsertionBars N
*  Dependencies: StdDraw.java
*
*  Insertion sort N random real numbers between 0 and 1, visualizing
*  the results by ploting bars with heights proportional to the values.
*
*  % java InsertionBars 20
*
******************************************************************************/

public class InsertionBars {
public static void sort(double[] a) {
int N = a.length;
for (int i = 0; i < N; i++) {
int j = i;
while (j >= 1 && less(a[j], a[j-1])) {
exch(a, j, j-1);
j--;
}
show(a, i, j);
}
}

private static void show(double[] a, int i, int j) {
StdDraw.setYscale(-a.length + i + 1, i);
StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
for (int k = 0; k < j; k++)
StdDraw.line(k, 0, k, a[k]*.6);
StdDraw.setPenColor(StdDraw.BOOK_RED);
StdDraw.line(j, 0, j, a[j]*.6);
StdDraw.setPenColor(StdDraw.BLACK);
for (int k = j+1; k <= i; k++)
StdDraw.line(k, 0, k, a[k]*.6);
StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
for (int k = i+1; k < a.length; k++)
StdDraw.line(k, 0, k, a[k]*.6);
}

private static boolean less(double v, double w) {
return v < w;
}

private static void exch(double[] a, int i, int j) {
double t = a[i];
a[i] = a[j];
a[j] = t;
}

public static void main(String[] args) {
int N = Integer.parseInt(args[0]);
StdDraw.setCanvasSize(160, 640);
StdDraw.setXscale(-1, N+1);
StdDraw.setPenRadius(.006);
double[] a = new double
;
for (int i = 0; i < N; i++)
a[i] = StdRandom.uniform();
sort(a);
}

}

package algorithms.elementary21;

import algorithms.util.StdDraw;
import algorithms.util.StdRandom;

/******************************************************************************
*  Compilation:  javac SelectionBars.java
*  Execution:    java SelectionBars N
*  Dependencies: StdDraw.java
*
*  Selection sort N random real numbers between 0 and 1, visualizing
*  the results by ploting bars with heights proportional to the values.
*
*  % java SelectionBars 20
*
******************************************************************************/

public class SelectionBars {

public static void sort(double[] a) {
int N = a.length;
for (int i = 0; i < N; i++) {
int min = i;
for (int j = i+1; j < N; j++)
if (less(a[j], a[min])) min = j;
show(a, i, min);
exch(a, i, min);
}
}

private static void show(double[] a, int i, int min) {
StdDraw.setYscale(-a.length + i + 1, i);
StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
for (int k = 0; k < i; k++)
StdDraw.line(k, 0, k, a[k]*.6);
StdDraw.setPenColor(StdDraw.BLACK);
for (int k = i; k < a.length; k++)
StdDraw.line(k, 0, k, a[k]*.6);
StdDraw.setPenColor(StdDraw.BOOK_RED);
StdDraw.line(min, 0, min, a[min]*.6);
}

private static boolean less(double v, double w) {
return v < w;
}

private static void exch(double[] a, int i, int j) {
double t = a[i];
a[i] = a[j];
a[j] = t;
}

public static void main(String[] args) {
int N = Integer.parseInt(args[0]);
StdDraw.setCanvasSize(260, 640);
StdDraw.setXscale(-1, N+1);
StdDraw.setPenRadius(.006);
double[] a = new double
;
for (int i = 0; i < N; i++)
a[i] = StdRandom.uniform();
sort(a);
}

}