Implement Array Random Shuffle - arrays

Question

Prelude
I am writing a grid-based random-map generator.
Currently, I want to populate a 2D array with a variety of tiles.
Problem
In the parenthesis is a more concrete example.
Here is what you are given:
2D array and its dimensions. (i.e. 3x4 grid)
Integer Random(Range) (i.e. Range: 0-11, Output: integer from 0-11)
You do NOT have a function that randomly sorts an array, unless you implement it yourself.
Number of each type of tile (i.e. Desert: 2, Lake: 4, Forrest: 6)
How do I populate this array with the given tiles?
Example
3x4 map; 6 Forrest; 4 Lake; 2 Desert...
F F L
L D F
D F F
L F L
Attempt
I do have my own implementation, however its Big-O is... infinity, I think. :)
Of course, the chances that it will never finish are slim; however, this is part of a video game and I don't want to keep the player waiting.
Postscript
I don't really care what language that it is implemented in; pseudo-code will be satisfactory.

Answer 1

make sure the inputs are correct (e.g. total count of tiles equals
the count of slots in the grid)
put all give tiles into a queue Q, whose length is n(in your
example, n=12)
intialize a result array R[p], p is intialized as 0
get k=random(1->n), deque Q[k] into R[p], p++
repeat step 4 until p goes to n
Things can be much more easier if you use a language that has built-in sort functions:
verify input
put given tiles into an one demension array A[n]
sort A[n] randomly
Code in C#:
int m = 3;
int n = 4; //m*n grid
int forrests = 6;
int lakes = 4;
int deserts = 2;
if (m * n != forrests + lakes + deserts)
{
//invalid input!
}
char[] tiles = new char[m * n];
for (int i = 0; i < m * n; i++)
{
if (i < forrests)
{
tiles[i] = 'F';
}
else if (i < forrests + lakes)
{
tiles[i] = 'L';
}
else
{
tiles[i] = 'D';
}
}
//preparation completed, now tiles[] looks like
//F,F,F,F,F,F,L,L,L,L,D,D
char[] output = tiles.OrderBy(t => Guid.NewGuid()).ToArray();
//output is randomly sorted from tiles
//if you really need a two-demension array
char[][] map = new char[n][];
for (int i = 0; i < n; i++)
{
map[i] = output.Skip(m * i).Take(m).ToArray();
}

Answer 2

This could one of the way to do it.
#include<iostream>
#include <cstdlib>
#include <map>
using namespace std;
//Map which keeps the value for each key (2,4,6)
map<int,char> alphabet;
void initMap()
{
alphabet[2] = 'D';
alphabet[4] = 'L';
alphabet[6] = 'F';
}
int main()
{
char a[3][4];
// counter variables to keep track of d,f and l
int temp,d=0,f=0,l=0;
initMap();
for(int i=0;i<3;i++)
{
for(int j=0;j<4;j++)
{
//This determines if the generated random number is already entered in the grid. If no than breaks out. If yes than again a new random number is generated and process is iterated untill the new number is found to enter
while(1)
{
temp = rand()%4;
if(temp==0)
{
temp = 2;
}
else
{
temp = temp*2;
}
if(temp ==2 && d<2)
{
d++;
break;
}
else if(temp ==4 && l<4)
{
l++;
break;
}
else if(temp ==6 && f<6)
{
f++;
break;
}
else
{
continue;
}
}
//char value for the number temp is assigned from the alphabet map
a[i][j] = alphabet.at(temp);
cout<<a[i][j]<<" ";
}
cout<<endl;
}
return 0;
}
output:
D F L D
L L L F
F F F F
You can map the alphabet according the number when entering the value or accessing the value from array.