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package algs14;
import stdlib.*;
public class XCountingLoops {
// To Print: StdOut.printf ("N=%3d i=%3d N-i=%d\n", N, i, N-i);
//
// Test variant with one, two or three nested loops
//
// Outermost:
// for (long i = 1; i <= N; i = i+1) {
// for (long i = 1; i <= N; i = i*2) {
//
// Next:
// for (long j = 1; j <= N; j = j+1) {
// for (long j = 1; j <= i; j = j+1) {
// for (long j = 1; j <= N; j = j*2) {
// for (long j = 1; j <= i; j = j*2) {
//
// Next:
// for (long k = 1; k <= N; k = k+1) {
// for (long k = 1; k <= j; k = k+1) {
// for (long k = 1; k <= N; k = k*2) {
// for (long k = 1; k <= j; k = k*2) {
// f counts the number of times the innermost loop executes
static long f (long N) {
long result = 0;
for (long i = 1; i <= N; i = i+1) {
for (long j = 1; j <= N; j = j+1) {
result = result+1;
if (N <= 64) StdOut.format ("%02d ", i);
}
if (N <= 64) StdOut.println ();
}
return result;
}
public static void main (String[] args) {
f(16);
long MIN = 256L; // for powers of ten, start with 500L
long MAX = 3_200_000_000L;
Stopwatch sw = new Stopwatch ();
double prevCount = f(MIN);
double prevTime = sw.elapsedTime ();
for (long N = MIN*2; N <= MAX; N=N*2) {
sw = new Stopwatch ();
long count = f(N);
double time = sw.elapsedTime ();
StdOut.format ("Elapsed count f(%,13d): %,16d: %10.3f [%10.3f : %10.3f]\n", N, count, count / prevCount, time, time/prevTime);
//StdOut.format ("Elapsed count f(%,13d): %,16d: %10.3f\n", N, count, count / prevCount);
prevCount = count;
prevTime = time;
}
}
}
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