Binary Search and Variations

#include<bits/stdc++.h>
using namespace std;

#define     fast            ios_base::sync_with_stdio(false);cin.tie(NULL)
#define     read            freopen("input.txt","r",stdin)
#define     write           freopen("output.txt","w",stdout)

int binary_search(int *arr, int low, int high, int target)
{
    while(low <= high)
    {
        int mid = low + (high - low) / 2;
        if(arr[mid] == target)
            return mid;
        else if(arr[mid] < target)
            low = mid + 1;
        else
            high = mid - 1;
    }
    return -1;
}

int lower_bound(int *arr, int low, int high, int target)
{
    while(low <= high)
    {
        int mid = low + (high - low) / 2;
        if(arr[mid] < target)
            low = mid + 1;
        else
            high = mid - 1;
    }
    return low;
}

int upper_bound(int *arr, int low, int high, int target)
{
    while(low <= high)
    {
        int mid = low + (high - low) / 2;
        if(arr[mid] <= target)
            low = mid + 1;
        else
            high = mid - 1;
    }
    return low;
}

int first_occurence(int *arr, int low, int high, int target)
{
    while(low <= high)
    {
        int mid = low + (high - low) / 2;
        if(arr[mid] < target)
            low = mid + 1;
        else
            high = mid - 1;
    }
    if(arr[low] == target)
        return low;
    else
        return -1;
}

int last_occurence(int *arr, int low, int high, int target)
{
    while(low <= high)
    {
        int mid = low + (high - low) / 2;
        if(arr[mid] <= target)
            low = mid + 1;
        else
            high = mid - 1;
    }
    if(arr[high] == target)
        return high;
    else
        return -1;
}

int main()
{
#ifndef ONLINE_JUDGE
    read;
    write;
#endif
    fast;
    int arr[] = {6, 6, 7, 9, 9, 9, 9, 10, 15, 17, 22};
    int n = sizeof(arr) / sizeof(arr[0]);
    int x = binary_search(arr, 0, n - 1, 9);
    int lb = lower_bound(arr, 0, n - 1, 9);
    int ub = upper_bound(arr, 0, n - 1, 9);
    int fo = first_occurence(arr, 0, n - 1, 9);
    int lo = last_occurence(arr, 0, n - 1, 9);
    cout << x << ' ' << lb << ' ' << ub << ' ' << fo << ' ' << lo << endl;
    return 0;
}