A simple algorithm that defines an array of length n, which stores all positive integers of 1 to N in random order, and does not repeat.

A few days ago I saw a small problem on the. NET written test set, which asked for a simple algorithm to randomly populate a positive integer from 1 to 100 into an array of length 100.

I'm free to write a little bit today. The code is as follows, the comments are more detailed:

1 usingSystem;2 usingSystem.Collections.Generic;3 usingSystem.Linq;4 usingSystem.Text;5 usingSystem.Text.RegularExpressions;6 7 namespaceTestnumber8 {9     class ProgramTen     { One         //define regular expressions that determine positive integers A          Public Static stringRegex ="^[1-9][0-9]*"; -         Static voidMain (string[] args) -         { the  -Console.WriteLine ("Please input a number!"); -             stringInputstr =console.readline (); -             //determines whether the input is a positive integer, or not, the End method +             if(!Regex.IsMatch (Inputstr,regex)) -             { +Console.WriteLine ("input format Error!"); A                return; at             } -             //Transform Shaping -             intinputnum=Convert.ToInt32 (INPUTSTR); -              -             //Creating an shaping collection, placing 1-N collections -list<int> numlist =Newlist<int>(); in              for(intj =1; J < inputnum+1; J + +) -             { to Numlist.add (j); +             } -             //define a random number instance theRandom r=NewRandom (); *             int[] Outputnum =New int[Inputnum]; $              for(inti =0; i < Inputnum; i++)Panax Notoginseng             { -                 //gets a random element of a collection the                 intK = R.next (0, inputnum-i); +                 //placing an element into an array AOutputnum[i] =Numlist[k]; the                 //collection to remove the element + Numlist.removeat (k); -             } $             foreach(varIinchoutputnum) $             { -Console.Write (i+","); -             } the  -         }Wuyi     } the}

The test exception results are as follows:

The normal results of the test are as follows:

Ok,that ' s all.

A simple algorithm that defines an array of length n, which stores all positive integers of 1 to N in random order, and does not repeat.