Created
October 5, 2011 21:25
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How fast is it: Picking the max out of 1 Mio ints
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import java.util.*; | |
public class HowFastIsMax { | |
private static final int INTEGERS_IN_LIST = 1000000; | |
private static final int TEST_RUNS = 10; | |
public static void main(String[] args) { | |
List<Integer> list = fillRandomIntList(); | |
for (int i = 0; i < TEST_RUNS; i++) { | |
long start = System.nanoTime(); | |
int max = searchIntListForMax(list); | |
long stop = System.nanoTime(); | |
long duration = stop - start; | |
System.out.format("Searching %d ints for max took %fms. Max was %d.\n", list.size(), duration / 1000000.0, max); | |
} | |
} | |
private static List<Integer> fillRandomIntList() { | |
List<Integer> list = new ArrayList<Integer>(INTEGERS_IN_LIST); | |
Random rand = new Random(); | |
for (int i = 0; i < INTEGERS_IN_LIST; i++) { | |
list.add(rand.nextInt()); | |
} | |
return list; | |
} | |
private static int searchIntListForMax(List<Integer> list) { | |
int max = Integer.MIN_VALUE; | |
for (Integer i : list) { | |
max = i > max ? i : max; | |
} | |
return max; | |
} | |
} | |
//Searching 1000000 ints for max took 13.822000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 2.658000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 3.528000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 2.451000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 2.489000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 2.688000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 2.689000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 2.545000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 2.649000ms. Max was 2147479115. | |
//Searching 1000000 ints for max took 2.414000ms. Max was 2147479115. |
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