Binary Search in C++

Welcome to the Binary Search in C++ page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

#include <iostream>
#include <bits/stdc++.h>

using namespace std;

void handle_error()
{
    cout << "Usage: please provide a list of sorted integers (\"1, 4, 5, 11, 12\") and the integer to find (\"11\")" << endl;
    exit(0);
}

int check(string s)
{
    int x1 = 0, x2 = s.size() - 1;

    for (int i = 0; i < s.size(); i++)
    {
        if (s[i] != ' ')
        {
            x1 = i;
            break;
        }
    }

    for (int i = s.size() - 1; i >= x1; i--)
    {
        if (s[i] != ' ')
        {
            x2 = i;
            break;
        }
    }

    for (int i = x1; i <= x2; i++)
    {
        if (s[i] == ' ')
        {
            handle_error();
        }
    }

    return stoi(s);
}

vector<int> convert(string s)
{
    if (s.size() == 0)
    {
        handle_error();
    }
    vector<int> v;
    string num = "";
    for (int i = 0; i < s.size(); i++)
    {
        if ((int)s[i] >= 48 && (int)s[i] <= 57 || s[i] == ' ')
        {
            num += s[i];
        }
        else if (s[i] == ',')
        {
            v.push_back(check(num));
            num = "";
        }
        else
        {
            handle_error();
        }
    }

    if (num.size() > 0)
    {
        v.push_back(check(num));
    }

    return v;
}

int main(int argc, char *argv[])
{
    if (argc < 3)
    {
        handle_error();
    }

    vector<int> v = convert(argv[1]);
    int num = check(argv[2]);

    for (int i = 0; i < v.size() - 1; i++)
    {
        if (v[i] > v[i + 1])
        {
            handle_error();
        }
    }

    int start = 0, end = v.size();
    string ans = "false";
    while (start < end)
    {
        int mid = (start + end) / 2;

        if (num < v[mid])
        {
            end = mid;
        }
        else if (v[mid] < num)
        {
            start = mid + 1;
        }
        else if (v[mid] == num)
        {
            ans = "true";
            break;
        }
    }

    if (start > end)
    {
        ans = "false";
    }

    cout << ans << endl;
}

Binary Search in C++ was written by:

• Jeremy Grifski
• Sailok Chinta

If you see anything you'd like to change or update, please consider contributing.

Note: The solution shown above is the current solution in the Sample Programs repository as of Oct 10 2022 16:05:09. The solution was first committed on Oct 27 2019 18:00:32. As a result, documentation below may be outdated.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.