An algorithm that produces a non-repeating random array (random array of elements)

Produces an unordered array of length 100, consisting of a number from 0 to 99, with different elements.

In other words, a continuous array of 0 to 100 is scattered.

by three different ways.

One: Using list and random numbers

  long s1 = system.currenttimemillis ();  //  list ar =  new arraylist ();  //   for  (int i = 0; i  < 100000; i++)  {//    ar.add (i);//   } //    int [] toArray = new int[100000];//   //    for (int j = 100000; j >0; j--) {//     double d   =  (Math.random () *j);//     int index =  (int) d;//      toArray[j-1]=  (int) ar.get (index);//     ar.remove ( Ar.get (index));//   } //   long s2 =  System.currenttimemillis ();  //   system.out.println ("S2-s1 spents:" + (S2&NBSP;-&NBSP;S1));  s2-s1:14881

Two. Create an unordered array by swapping the position of the original array element instead of removing the elements from the original collection

   long s1 = system.currenttimemillis ();      int [ ] ar = new int[100];   for  (int i = 0; i <  100; i++)  {       ar[i]=i;   }     int [] toarray = new int[100];    for (int j  = 100; j >0; j--) {     int index  =  (int) (Math.random () *j);          toarray[j-1]= ar[index];      int temp  = ar[index];     ar[index ] = ar[j-1];     ar[j-1] = temp;   }    long s2 = system.currenttimemillis ();    system.out.println ("S2-S1:" + (s2 &NBSP;-&NBSP;S1));

Three: Define a switch for each element of the original array, determine whether the element repeats through the switch, and if the repetition continues to generate a random number, know not to repeat

  long s1 = system.currenttimemillis ();    //counters   tags How many times is this method circulating?    int c = 0;     //This is 0-99 number   int[] iqs  = new int[100000];  for  (int i = 0; i < 100000 ;  i++)  {   iqs[i] = i;  }   //This is a random array    int[] sb = new int[100000];  //Setting Switch   boolean[] b = new  boolean[100000];  //Assignment   for  (int i = 0; i <  100000; i++)  { //  traversing IQs array    int index;   do {     c++;    index =  (int)   (math.random ()  *  iqs.length);  // iqs array random subscript    } while  (b[index] == true);  //  b[index] generates a corresponding character for true code, the subscript is rebuilt        sb[i] = iqs[index]; //  Remove the elements from the IQs to each element of SB        b[index] = true; //  True indicates that   }     system.out.println (c) has been generated;    long s2  = system.currenttimemillis ();    system.out.println (S2&NBSP;-&NBSP;S1);   return sb;

This article is from the "Java Stuff" blog, so be sure to keep this source http://1027187712.blog.51cto.com/5509347/1628020

An algorithm that produces a non-repeating random array (random array of elements)