Count Triplets Hacker Rank Problem Solution

Count Triplets Hacker Rank Problem Solution->

Problem Statement->

You are given an array and you need to find number of tripets of indices  such that the elements at those indices are in geometric progression for a given common ratio  and .

For example, . If , we have  and  at indices  and .

Function Description

Complete the countTriplets function in the editor below. It should return the number of triplets forming a geometric progression for a given  as an integer.

countTriplets has the following parameter(s):

• arr: an array of integers
• r: an integer, the common ratio

Input Format

The first line contains two space-separated integers  and , the size of  and the common ratio.
The next line contains  space-seperated integers .

Constraints

Output Format

Return the count of triplets that form a geometric progression.

///link of question->https://www.hackerrank.com/challenges/count-triplets-1/problem?h_l=interview&playlist_slugs%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D=dictionaries-hashmaps on HackerRank

 

My Code->

#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);

string rtrim(const string &);

vector<string> split(const string &);

// Complete the countTriplets function below.

long countTriplets(vector<long> arr, long r) {

   // arr.sort(arr.begin(),arr.end());

    map<long long int  ,long long int > lmap;

    map<long long int  ,long long int > rmap;

    for(int i=0;i<arr.size();i++){

       rmap[arr[i]]++;

    }

    long long int  count=0;

    for(int i=0;i<arr.size();i++){

        long long int  f=arr[i]/r;

        long long int s=arr[i];

        long long int t=arr[i]*r;

         rmap[arr[i]]--;

           if(arr[i]%r==0){

               count+=lmap[f]*rmap[t];

           }

            lmap[arr[i]]++;

           //cout<<"inside";

    }

    return count ;

}

int main()

{

    ofstream fout(getenv("OUTPUT_PATH"));

    string nr_temp;

    getline(cin, nr_temp);

    vector<string> nr = split(rtrim(nr_temp));

    int n = stoi(nr[0]);

    long r = stol(nr[1]);

    string arr_temp_temp;

    getline(cin, arr_temp_temp);

    vector<string> arr_temp = split(rtrim(arr_temp_temp));

    vector<long> arr(n);

    for (int i = 0; i < n; i++) {

        long arr_item = stol(arr_temp[i]);

        arr[i] = arr_item;

    }

    long ans = countTriplets(arr, r);

    fout << ans << "\n";

    fout.close();

    return 0;

}

string ltrim(const string &str) {

    string s(str);

    s.erase(

        s.begin(),

        find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))

    );

    return s;

}

string rtrim(const string &str) {

    string s(str);

    s.erase(

        find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),

        s.end()

    );

    return s;

}

vector<string> split(const string &str) {

    vector<string> tokens;

    string::size_type start = 0;

    string::size_type end = 0;

    while ((end = str.find(" ", start)) != string::npos) {

        tokens.push_back(str.substr(start, end - start));

        start = end + 1;

    }

    tokens.push_back(str.substr(start));

    return tokens;

}