Get sorted order indices from an unsorted array

Question

1.00/5 (1 vote)

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I need a program to return the sorted order indices from an array of numbers:

a[4] = {10,7,2,3}; // input
b[4] = {4,3,1,2}; // expected output

In a[4] lowest element is 2 (arrayindex = 2), output value of array index 2 should be append to 1, and 2nd lowest element is 3 (array index = 3), output value of array index 3 should be append to 2.

Can any one help with this program?

Regards
Steve

Posted 19-Jan-11 1:48am

Stephen7

Updated 19-Jan-11 3:36am

Nish Nishant

v5

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Comments

Espen Harlinn 19-Jan-11 7:50am

exam?

#realJSOP 19-Jan-11 7:53am

Your examples don't make any sense at all, and your description doesn't help.

Kasson 19-Jan-11 8:10am

You want your Homework to be done by Us?

Aescleal 19-Jan-11 10:31am

Can anyone help with the specification?

2 solutions

Solution 1

Since your 'output array' looks containing just the order of the corrensponding item of the input array (when increasingly ordered), you may do:

C

int i, j;
for (i = 0; i < 4; i++)
{
  b[i] = 0;
  for (j = 0; j < 4; j++)
  {
    if (a[i] >= a[j]) 
      b[i]++;
  }
}

:)

Posted 19-Jan-11 2:12am

CPallini

Updated 19-Jan-11 2:13am

v2

Comments

Andrew Brock 20-Jan-11 3:34am

Sorry, forgot to vote your answer. 5

CPallini 20-Jan-11 3:36am

Oh it doesn't matter (and you shouldn't rate it 5 if you think it is poorly explained), anyway, thank you :-).

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Andrew Brock · Accepted Answer · 2011-01-19T02:16:00

After reading your question 5 times I think I understand what u want.

I was going to try and clarify what you are trying to do better, but it is a rather tricky thing to explain ;P

This code produces the same output as your variable b.

#include <stdio.h>
#include <limits.h>
int main() {
    int pGapArray[] = { 10, 7, 2, 3 }; //Your a[], the input array
    int pNoGapArray[sizeof(pGapArray) / sizeof(pGapArray[0])];
    int nLowestIdx = 0; //This is equal to the index of the lowest number yet to be processed
    int nLowestVal = INT_MAX; //This is equal lowest number yet to be processed
    int nMinLowest = -1; //This is equal to the highest number we have processed
    int nValue = 1; //This is equal to the value we are writing to pNoGapArray
    for (int nIndex = 0; nIndex < sizeof(pGapArray) / sizeof(pGapArray[0]); ++nIndex) {
        nLowestVal = INT_MAX; //Reset the lowest value found
        for (int nSearch = 0; nSearch < sizeof(pGapArray) / sizeof(pGapArray[0]); ++nSearch) {
            if (pGapArray[nSearch] < nLowestVal && pGapArray[nSearch] > nMinLowest) {
                nLowestIdx = nSearch;
                nLowestVal = pGapArray[nSearch];
            }
        }
        nMinLowest = pGapArray[nLowestIdx];
        pNoGapArray[nLowestIdx] = nValue++;
    }
    printf("  pGapArray[] = { ");
    for (int nIndex = 0; nIndex < sizeof(pGapArray) / sizeof(pGapArray[0]); ++nIndex) {
        printf("%d, ", pGapArray[nIndex]);
    }
    printf("};\n");
    printf("pNoGapArray[] = { ");
    for (int nIndex = 0; nIndex < sizeof(pNoGapArray) / sizeof(pNoGapArray[0]); ++nIndex) {
        printf("%d, ", pNoGapArray[nIndex]);
    }
    printf("};\n");
    return 0;
}