Sort not full inserted Array

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I have an array of size 100, and some of its values are numbers and others are null.
Let's say [NULL][NULL][5][4][NULL][6]...
I try to sort the array with it's valid numbers.
Can I have a link to a sample explanation code?

Edit:
Array should be [NULL][NULL][4][5][NULL][6]...

Posted 30-Oct-11 10:29am

kadmf

Updated 30-Oct-11 10:34am

v2

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3 solutions

Solution 1

so you just want to sort the "sub" arrays between the null entries ?

you could (I haven't tested it) loop the array to find the first and last index of each sequence and pass that to stl's sort, I think it works with arrays (you pass the index/addresses of the arrays.

good luck.

M.

Posted 30-Oct-11 11:13am

Maximilien

Comments

CPallini 30-Oct-11 17:39pm

[Moved from OP fake answer] Not quite there can be NULLS between numbers like
[null][5][null][null][2][null][3] -> [null][2][null][null][3][null][5]

Solution 4

We can also process an <int*> array
whose NULL-elements are "not inserted" but other elements can be 0 as well :)

C++

#include <stdlib.h>

int yourCompareFunc(const void *arg1, const void *arg2)
{
  if (arg1 && arg2) {
    return (*(int*)arg1) - (*(int*)arg2);
  }
  return 0;
}


void yourSort(int* piElements, int iElementsCount)
{
  qsort(piElements, iElementsCount, sizeof(int*), yourCompareFunc);
}

Posted 30-Oct-11 21:22pm

Eugen Podsypalnikov

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CPallini · Accepted Answer · 2011-10-30T11:37:00

Try the following steps:

Record (valid) values and their positions in two new arrays.
Sort array of values (you may now use any of the 'ordinary' sorting method like, for instance, std::sort).
Use both the array of positions and the one of ordered values to replace numbers into the original array.

namely:

C++

#include <vector>
#include <algorithm>
using namespace std;

void mySort(int a[], size_t size)
{
  vector < int > pos;
  vector < int > val;
  for (size_t i=0; i<size; i++)
  {
    if ( a[i] != NULL)
    {
      pos.push_back(i);
      val.push_back(a[i]);
    }
  }

  sort(val.begin(),val.end());

  for (size_t i=0; i<pos.size(); i++)
    a[pos[i]] = val[i];
}