java는 간단한 demo 실례를 사용하여 최적화 알고리즘의 강함을 알려준다

/**
      *  
      * @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;
     }

/**
      *  :<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;
     }

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

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

     /**
      *  
      * @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;
     }

     /**
      *  :<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;
     }

     public static void main(String[] args) {
         // ， 
         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(" [1] ["+value+"]  ： ["+(end - start) + "]ms, ："+ sum);
         // ， 
         System.gc();
         start = System.currentTimeMillis();
         sum = gaosi(value);
         end = System.currentTimeMillis();
         System.out.println(" [1] ["+value+"]  ： ["+(end - start) + "]ms, ："+ sum);

     }

 }

 [1] [10000000]  ： [24]ms, ：50000005000000
 [1] [10000000]  ： [0]ms, ：50000005000000