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

int linear_search(vector<int> arr, int key)
{
    for (int i = 0; i < arr.size(); i++)
        if (arr[i] == key)
            return i;

    return -1;
}

int binary_search(vector<int> arr, int key)
{
    int l = 0;
    int r = arr.size() - 1;

    while (l <= r) {
        int mid = (l + r) / 2;
        if (arr[mid] == key)
            return mid;
        else if (arr[mid] < key)
            l = mid + 1;
        else
            r = mid - 1;
    }

    return -1;
}

int main()
{
    vector<int> arr(10000000);
 
    //sorted input 1 to 10000000
    for (int i = 0; i < 10000000; i++)
        arr[i] = i + 1;

    //we will search 5 keys
    //key1=3000000
    //key2=5000000
    //key3=7000000
    //key4=9000000
    //key5=11000000
 
    vector<int> keys{ 3000000, 5000000, 7000000, 9000000, 11000000 };
   
 
   
    // Linear Search time
    for (int i = 0; i < 5; i++) {

        int res = linear_search(arr, keys[i]);
        if (res != -1)
            cout << "Key found at : " << res << endl;
        else
            cout << "Key not found\n";
    }
   
    // Binary Search time
    for (int i = 0; i < 5; i++) {
        int res = binary_search(arr, keys[i]);
        if (res != -1)
            cout << "Key found at : " << res << endl;
        else
            cout << "Key not found\n";
    }
   

    return 0;
}

Output

Key found at : 2999999
Key found at : 4999999
Key found at : 6999999
Key found at : 8999999
Key not found
Key found at : 2999999
Key found at : 4999999
Key found at : 6999999
Key found at : 8999999
Key not found