Question

How to check if product of every adjacent pairs exists in a vector with C++

Answer 1

#include <iostream>
#include <unordered_set>
#include <vector>

bool check_product_of_every_pair(const std::vector<int>& vec) {
    std::unordered_set<int> set(vec.begin(), vec.end());

    for (size_t i = 0; i < vec.size(); i += 2) {
        int product = vec[i] * vec[i + 1];
        std::cout << vec[i] << " * " << vec[i + 1] << " = " << product << "\n";
        if (set.find(product) == set.end()) {
            return false;
        }
    }

    return true;
}
 
int main()
{
    std::vector<int> vec = {2, 3, 6, 5, 30, 0};

    std::cout << (check_product_of_every_pair(vec) ? "Yes" : "No");
}



/*
run:

2 * 3 = 6
6 * 5 = 30
30 * 0 = 0
Yes

*/

 

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Answer 2

#include <iostream>
#include <algorithm>
#include <vector>
 
bool check_product_of_every_pair(const std::vector<int>& vec) {
    for (size_t i = 0; i < vec.size(); i += 2) {
        int product = vec[i] * vec[i + 1];
        std::cout << vec[i] << " * " << vec[i + 1] << " = " << product << "\n";
        if (std::count(vec.begin(), vec.end(), product) == 0) {
            return false;
        }
    }
 
    return true;
}
  
int main()
{
    std::vector<int> vec = {2, 3, 6, 5, 30, 0};
 
    std::cout << (check_product_of_every_pair(vec) ? "Yes" : "No");
}
 
 
 
/*
run:
 
2 * 3 = 6
6 * 5 = 30
30 * 0 = 0
Yes
 
*/

 

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