Ali Abdel Samie Ali Abdel Samie - 1 year ago 79
C++ Question

find the max product of 2 array element

i tried to find the max product of 2 array element so my idea is to sort the array and multiply the last 2 elements. my code is working with different test cases but in test case .
100000 90000
it has wrong answer only in this test case !
Here is my code

#include <iostream>
using namespace std;

int main()
int n;
cin >> n ;
int arr [n];

for (int i=0; i<n; i++)
cin>> arr[i] ;
for (int i=0; i<n; i++)
for(int j=i+1; j<=n; j++)
if (arr[j]<arr[i])
swap(arr[j],arr[i]) ;

cout <<arr[n-1]<<" "<<arr[n-2] <<endl;
int res = arr[n-1] * arr[n-2];
cout << res ;


Answer Source

The following code should work:

#include <vector>
#include <algorithm>
#include <iostream>

int main()
    int num = 0, size = 0;
    std::cin >> size;
    std::vector<int> numbers(size);
    for (int counter = 0; counter < size; counter++) {
        std::cin >> num;
        numbers[counter] = num;

    std::sort(numbers.begin(), numbers.end());
    int max = numbers[size - 1] * numbers[size - 2];
    std::cout << max << std::endl;

Since you are utilizing Variable Length Arrays, why not just use a vector?

The code above gets numbers from std::cin, and puts them into the vector. The vector is then sorted. We have a variable for the size of vector - 1, so we don't go out of bounds accessing our elements. max is the initialized to the product of the last two elements of the vector. Finally, the product gets printed.

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