Program Analysis Jobs

To read the following procedure, please answer the following questions:

Question 1: What are the criteria for this program?

Question 2: Does such a number exist? What is the minimum number that meets this condition?

Question 3: How long do you expect to be able to output the first result when running this program on a computer? The time is accurate to minutes (computer: Single core CPU 4.0G Hz, memory and hard disk resources are sufficient).

Question 4: How can I improve the efficiency of this program on multi-core computers?

(Note: This program, written in C # language, but as long as there is no reading pressure on the basis of C language, if you do not understand some of the statements, please check yourself)

Write the results of the above questions on the blog, Deadline this Sunday (March 19) 8 o'clock in the evening

Using System;

Using System.Collections.Generic;

Using System.Text;

Namespace Findthenumber

{
Class Program
{
static void Main (string[] args)
{
int [] RG =
{2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,
20,21,22,23,24,25,26,27,28,29,30,31};
for (Int64 i = 1; i < int64.maxvalue; i++)
{
int hit = 0;
int hit1 =-1;
int hit2 =-1;
for (int j = 0; (J < RG. Length) && (hit <=2); J + +)
{
if ((i% rg[j])! = 0)
{
hit++;
if (hit = = 1)
{
Hit1 = j;
}
else if (hit = = 2)
{
Hit2 = j;
}
Else
Break
}

}
if (hit = = 2) && (HIT1+1==HIT2))
{
Console.WriteLine ("Found {0}", i);
}
}
}
}
}

For:

1. According to the Code analysis, the program defines I as a number: between 2 and 31, only two consecutive numbers can not be divisible by I, the rest of the number is divisible by I, so this number is to remove the two consecutive numbers, all the number of least common multiple.

2. This number I exists. The smallest number that fits this feature I didn't figure out, should be very big, 10^12 above.

3. Running this program on a computer should take a very long time to reach this number. Because it is the least common multiple of the remaining 28 numbers, the program is probably going to perform this least common multiple cycle, and then the calculation time should be at least 10000min.

4. On the web and in the Forum to see the increase in the efficiency of the program, the program can be optimized algorithm to improve operational efficiency. (By reading someone else's blog, I learned that multicore CPUs can also perform the next loop at the same time I perform a loop, which can be almost several times more efficient.) ）

Program Analysis Jobs