TernarySearch.cpp

#include <bits/stdc++.h>
using namespace std;
 
int ternarySearch(int l, int r, int key, int ar[])
{
    if (r >= l) {
 
        
        int mid1 = l + (r - l) / 3;
        int mid2 = r - (r - l) / 3;
 
        if (ar[mid1] == key) {
            return mid1;
        }
        if (ar[mid2] == key) {
            return mid2;
        }
        if (key < ar[mid1]) {
            return ternarySearch(l, mid1 - 1, key, ar);
        }
        else if (key > ar[mid2]) {
            return ternarySearch(mid2 + 1, r, key, ar);
        }
        else {
            return ternarySearch(mid1 + 1, mid2 - 1, key, ar);
        }
    }
    return -1;
}
 
int main()
{
    int n ,l, r, p, key;
    cin >> n ;
    int *ar = new int[n] ;
    // taking input array
    for(int i = 0 ; i < n ;i++){
        cin >> ar[i] ;
    }
    
    cout << "enter key ";
    cin >> key ; 

    l = 0;
    r = n;
    cout << r ; 

    p = ternarySearch(l, r, key, ar);
 
    // Print the result
    cout << "Index of " << key << " is " << p << endl;
    
}