CODEWITHSUNDEEP
c++arrayssorting
Anna
Anna

Reputation: 3

Need help excluding certain things from my array

I need to output stalls which made profit (if they made profit) in increasing order of profit (lowest profit to highest profit). When I run my program, it outputs it in increasing order but only excludes one instance of profit that is < 0 and outputs the rest. What am I doing wrong?

Below is the code I'm using to exclude stalls that made a profit of < 0

    for (int i = 0; i < n; i++){
        if (Stalls[i].net < 0){
            for (int j = i + 1; j < n; ++j){
            Stalls[j - 1] = Stalls[j];}
            n--;}

}

    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            if (Stalls[i].net > Stalls[j].net) {
                Stall tmp = Stalls[i];
                Stalls[i] = Stalls[j];
                Stalls[j] = tmp;
            }
        }
    }
    for (int i = 0; i < n; i++)
        of << Stalls[i].name << endl;

Upvotes: 0

Views: 58

Answers (1)

Randy Firfield
Randy Firfield

Reputation: 27

My answer is not complete answer, but I found the main problem on the code.

# Remove negative items
for (int i = 0; i < n; i++)
{
    if (Stalls[i].net < 0)
    {
        printf(" i = %d, %d\n", i, Stalls[i].net);
        for (int j = i + 1; j < n; ++j)
        {
            // strcpy(Stalls[j - 1].name, Stalls[j].name);
            // Stalls[j - 1].net = Stalls[j].net;
            Stalls[j - 1] = Stalls[j];
        }
        n--;
    }
}

This function have problem

If data is [-3, -2, -1, 0, 1, 2]
After above for loop, data is [-2, 0, 1, 2, 2, 2]
But, we can think, the data is [0, 1, 2, 2, 2, 2]

Why:
-3 -2 -1 0 1 2

The index of -3 is 0,
With Stalls[j - 1] = Stalls[j];, -3 is replace with -2,
and -2 move to 0th position,

But, -2 cannot check with if (Stalls[i].net < 0), because the i is already increased

So, the -2 is remain

Easily answer: (Not optimized)

// Remove negative items
for (int k = 0; k < n; k++) // This is added loop
    for (int i = 0; i < n; i++)
    {
        if (Stalls[i].net < 0)
        {
            printf(" i = %d, %d\n", i, Stalls[i].net);
            for (int j = i + 1; j < n; ++j)
            {
                // strcpy(Stalls[j - 1].name, Stalls[j].name);
                // Stalls[j - 1].net = Stalls[j].net;
                Stalls[j - 1] = Stalls[j];
            }
            n--;
        }
    }

Upvotes: 1

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