(20140707 homework) As soon as you enter it, it is like a sea. From now on, it is a passer-by !~ 9*9 multiplication table & prime number within a thousand

This is the first day of training for our boss. In the future, almost all assignments will be recorded here.

2014-07-07

Requirements:

C # basic syntax to implement the 9-9 multiplication table and all prime numbers within 1000

 

A few new colleagues, who have just graduated from college, have an electromechanical background, and have hardware.

You may have different ideas, so you can brainstorm. For good ideas, I will learn from and retain them here.

 

Code of the bigbench:

1 // calculate the prime number less than 2 using system; 3 using system. collections. generic; 4 using system. LINQ; 5 using system. text; 6 using system. threading. tasks; 7 8 namespace Sushu 9 {10 class program11 {12 static void main (string [] ARGs) 13 {14 datetime d1 = system. datetime. now; // The current running time 15 console. writeline ("Start Time: {0}", D1); 16 console. writeline (); 17 18 int n = 10000; // defined range: 19 int m = 0; 20 bool T = false; // defines the existence variable of the factor, initially fa Lse21 int COUNT = 0; // count the number of variables 22 23 for (INT I = 1; I <= N; I ++) 24 {25 if (I = 2 | I = 3) // process 2 326 {27 COUNT = count + 1; 28 console. write ("{0}", I); 29} 30 31 if (I % 2! = 0) // exclude 32 {33 34 for (int A = 2; A <= I/2; A ++) // process a factor other than 1 (if there is a factor, there will inevitably be a factor smaller than n/2) 35 {36 T = false; 37 m = I %; 38 If (M = 0) 39 break; // The entire division exit loop 40 else41 T = true; // Key Identifier 42} 43 44 If (t = true) // judge the prime number, and then output the statistical quantity 45 {46 COUNT = count + 1; 47 console. write ("{0}", I); 48 if (count % 12 = 0) // output number typographical 12 columns 49 {50 console. writeline (); 51} 52} 53 54} 55 56} 57 console. writeline (); 58 console. writeline ("the total number of prime numbers within {0} is: {1}", N, count); // output prime number statistics 59 console. writeline (); 60 timespan Ts = datetime. now-D1; // obtain the current time and calculate the time consumption 61 console. writeline ("Time consumed: {0} seconds, {1} milliseconds", ts. seconds, ts. milliseconds); // output time-consuming data 62 63 64 console. readkey (); 65 66} 67} 68}

View code

 

Comment from the boss: (Here we only record what I understood at the time. The original words are not clearly remembered)

Its advantage is to minimize the number of cycles and eliminate certain non-prime numbers.

 

Xiao Yong's code:

1 static void main (string [] ARGs) 2 3 {4 5 Int I = 0, j = 0; 6 for (I = 3; I <= 10000; I = I + 2) // I + 2 remove the elements, reduce the calculation workload by 7 {8 // re-reduce the calculation workload, and combine element decomposition, the minimum factor must be 9 int K = (INT) math. SQRT (I); 10 for (j = 2; j <= K; j ++) 11 {12 // judge the prime number 13 if (I % J) = 0) 14 {15 break; 16} 17} 18 // If j <K, it indicates that no judgment is complete. Send it back and Judge 19 if (j> K) 20 {21 console. write (I. tostring () + ""); 22} 23} 24 console. read (); 25 26}

View code

 

Here we use a mathematical method (kaifang ):

1 int K = (INT) math. SQRT (I );

 

After asking the boss about the efficiency of running the function, the result is that the function uses a very good algorithm (not specifically remembered) in ancient China, but the speed is the slowest.