Java uses a simple demo example to show you the power of the optimization algorithm

Author：Eve Cole Update Time：2024-11-18 20:24:01

The demo here is an accumulation algorithm, such as 1,2,3,4...n

That is: sum = 1+2+3+4...+n;

We can do this:

Copy the code code as follows:

/**
* Loop to implement accumulation method
* @param value
* @return
*/
private static long cycle(long value) {
long sum = 0;

for (long i = 1,v = value; i <= v; i++) {
sum += i;
}
return sum;
}

Another method (Gaussian method):

Copy the code code as follows:

/**
* Gaussian method:<code>(n+1)*n/2</code><br>
* you can read more from <a href="http://zhidao.baidu.com/question/411055258.html">Here</a>
* @param value
* @return
*/
private static long gaosi(long value) {
long sum = 0;
sum = (value + 1) * value / 2;
return sum;
}

We can write a demo to test their differences:

Copy the code code as follows:

/**
*
*/
package com.b510.arithmetic;

/**
* Implementation of accumulation algorithm<br>
*
* @date 2013-4-16
* @author hongten
*
*/
public class AddArithmetic {

/**
* Loop to implement accumulation method
* @param value
* @return
*/
private static long cycle(long value) {
long sum = 0;

for (long i = 1,v = value; i <= v; i++) {
sum += i;
}
return sum;
}

public static void main(String[] args) {
//Clean up the memory, but it may not be executed.
System.gc();
// you should change value, then get the different results
long value = 10000000;
long sum = 0;
long start = System.currentTimeMillis();
sum = cycle(value);
long end = System.currentTimeMillis();
System.out.println("Use the loop accumulation method to accumulate from [1] to ["+value+"], time taken: ["+(end - start) + "]ms, result: "+ sum);
//Clean up the memory, but it may not be executed.
System.gc();
start = System.currentTimeMillis();
sum = gaosi(value);
end = System.currentTimeMillis();
System.out.println("Use Gaussian method to accumulate from [1] to ["+value+"], time taken: ["+(end - start) + "]ms, result: "+ sum);

}

You can change the value of the value in the main method to test the system time they consume....

Of course, the running results of machines with different configurations are different...

The operation status of my machine:

Copy the code code as follows:

Using the loop accumulation method to accumulate from [1] to [10000000] takes: [24]ms, result: 50000005000000
Using the Gaussian method to accumulate from [1] to [10000000] takes: [0]ms, result: 50000005000000