01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
|
package ds1.student.orderofgrowth;
import stdlib.StdOut;
import stdlib.Stopwatch;
public class PerformanceOfArrays {
private double[] a;
private int N;
public PerformanceOfArrays() {
this.a = new double[1];
this.N = 0;
}
private void resize(int capacity) {
double[] temp = new double[capacity];
for (int i = 0; i < N; i+=1) {
if (SHOW) StdOut.format ("%02d ", i);
temp[i] = a[i];
ops += 1;
}
if (SHOW) StdOut.println();
a = temp;
}
public void append(double item) {
if (N == a.length) resize (1+N); //resize((int)Math.ceil (N*1.5));
a[N] = item;
N += 1;
ops += 1;
}
private static long ops;
private static boolean SHOW = true;
public static void main(String[] args) {
timeTrial(32);
SHOW = false;
int MIN = 256;
int MAX = 100_000_000;
double prevTime = timeTrial(MIN);
double prevOps = ops;
double deltaSum = 0;
int deltaNum = 0;
for (int N = MIN*2; N<=MAX; N += N) {
double time = timeTrial(N);
StdOut.format ("Elapsed count f(%,13d): %,17d: %10.3f [%10.3f : %10.3f]\n", N, ops, ops / prevOps, time, time/prevTime);
prevTime = time;
deltaSum += ops/prevOps;
deltaNum += 1;
prevOps = ops;
}
StdOut.format ("Average delta: %.3f\n", deltaSum/deltaNum);
}
public static double timeTrial(int N) {
ops = 0;
Stopwatch s = new Stopwatch();
PerformanceOfArrays perfOfArrays = new PerformanceOfArrays();
for (int j=0; j<N; j+=1) {
perfOfArrays.append(j);
}
return s.elapsedTime();
}
}
|
