How to improve on this solution (C++ array iteration)?

Question

This is my solution to the problem of finding a value inside a C++ array:

#include <iostream>
#include <sys/resource.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h> 
#include <sys/types.h>
#include <algorithm>
#include <vector>

using namespace std;

class Answer
{
public:
    static bool exists(int ints[], int size, int k)
    {
        bool result = false;        
        for (int i = 0; i < size; i++)
        {
            if (ints[i] == k)
                result = true;
        }
        return result;
    }
};

The grader took points off citing the following reasons:

What could I have done to meet their requirements?

Do you understand what "binary search" is? If so, your code doesn't do that, and I see a big red X on the item marked as such. — PaulMcKenzie
– PaulMcKenzie, Commented Jun 24, 2022 at 4:19
The second thing is that you keep looping after you've found a result. At the very least, you should break out of the loop when you find the value. — PaulMcKenzie
– PaulMcKenzie, Commented Jun 24, 2022 at 4:22
Re: "What could I have done to meet their requirements?" Normally reading the question carefully helps a lot with this. — Willem
– Willem, Commented Jun 24, 2022 at 7:08

Camilo Vera · Accepted Answer · 2022-06-24 04:24:41Z

1

You are not implementing binary search, you could use binary_search or do it manually:

binary_search:

class Answer
{
public:
    static bool exists(int ints[], int size, int k)
    {
      return binary_search(ints, ints + size, k);
    }
};

manually:

class Answer
{
public:
    static bool exists(int ints[], int size, int k)
    {
      int low = 0;
      int high = size - 1;
      while (low <= high)
      {
        int mid = (low + high) / 2;
        if (ints[mid] == k)
        {
          return true;
        }
        else if (ints[mid] < k)
        {
          low = mid + 1;
        }
        else
        {
          high = mid - 1;
        }
      }
      return false;
    }
};

answered Jun 24, 2022 at 4:24

Camilo Vera

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