Lower bound

///Finding lowerbound by two method
#include<bits/stdc++.h>
using namespace std;
/*int l_bound(int arr[],int n,int k)
{
    int lo=0,hi=n-1,ans=-1;
    while(lo<=hi)
    {
        int mid=(lo+hi+1)/2;
        if(arr[mid]==k){
            ans=mid;
            hi=mid-1;
        }
        else if(k<arr[mid])
            hi=mid-1;
        else
            lo=mid+1;
    }
    return ans;
}
int main()
{
    int arr[7]={1,2,2,2,3,4,5};
    cout<<"lower bound of 2 is: ";
    cout<<l_bound(arr,7,2);
}*/

vector<int>vec;
int lo_bound(int k)
{
    int low_range=0,high_range=vec.size()-1,ans=-1;
    while(low_range<=high_range)
    {
        int mid_range=(low_range+high_range)/2;
        if(vec[mid_range]==k)
        {
            ans=mid_range;
            high_range=mid_range-1;
        }
        else if(k<vec[mid_range])
        {
            high_range=mid_range-1;
        }
        else
            low_range=mid_range+1;
    }
    return ans;

}
int main()
{
    int n;
    cout<<"Enter how many element"<<endl;
    cin>>n;
    cout<<"Enter values are:"<<endl;
    while(n!=0)
    {
        int value;
        cin>>value;
        vec.push_back(value);
        n--;
    }
    cout<<"which value lower bound you want to find: ";
    int k;
    cin>>k;
    cout<<"Lower bound is: "<<lo_bound(k);
}