i am not getting this answer of maxpairwiseproduct

Question

#include <cstdlib>
#include <iostream>
#include <vector>

using std::vector;
using std::cin;
using std::cout;

long long MaxPairwiseProduct(const vector<int>& numbers) {
  long long result = 0;
  int n = numbers.size();
  for (int i = 0;i<n;++i) {
    for (int j = i+1;j<n;++j) {
      if (((long long)numbers[i])*numbers[j])>result) {
        result = ((long long)(numbers[i]))*numbers[j];  
      }
    }  
  }
  return result;
}

long long MaxPairwiseProductFast(const vector<int>& numbers)
 {int n = numbers.size();
 
 int max_index1 = -1;
 for(int i = 0;i<n;++i)
   if ((max_index1 == -1) || (numbers[i] > numbers[max_index1]))
    max_index1 = i;
    
 int max_index2 = -1;
 for(int j = 0;j<n;++j)
   if ((j !=max_index1) && (max_index2 == -1) || (numbers[j] > numbers[max_index1]))
    max_index2 = j;
    cout <<max_index1 << ' ''<<max_index2 <<"\n";
 }
 
 int main() {
   while (true) {
    int n = rand() % 4 + 2;
    cout << n << "\n";
    vector<int>a;
     for (int i = 0;i<n;++i) {
       a.push_back(rand()% 10);
     }
     for(int i=0 ; i<n ; ++i) {
       cout <<a[i]<< ' ';
     }
     cout <<"\n";
     long long res 1 =MaxPairwiseProduct(a);
     long long res 2 =Fast(a);
     if (res1 !=res2) {
      cout<< "wrong answer: "<< res1 << ' ' << res2 << "\n";
      break;
     }
    else {
        cout << "OK\n";
    }
   }
   int n;
   cin >> n;
   vector<int> numbers(n);
   for (int i=0;i<n; ++i) {
     cin >> numbers[i];  
   }
   long long result = MaxPairwiseProductFast(numbers);
   cout << result << "\n";  
   return = 0;
   }
 }

Answer 1

Your code has plenty of errors. Just try to run and you'll see them and can fix them one by one:

• line 34: extra single quote, remove it.
• line 14: extra closing parenthesis after numbers[i], remove it.
• line 49: space in variable name is not allowed
• line 50: space in variable name is not allowed
• line 50: the method Fast() does not exist. Did you mean MaxPairwiseProductFast()?
• line 67: setting up the return value to 0 is return 0; not return = 0;
• extra (unneeded) closing brace in the last line. Remove it.

After you fix these, the code runs. (I didn't have the time to check if it does the right thing -- not even sure what your code is supposed to do -- but the program starts, it has some output and it does not crash.)

#include <iostream>
#include <vector>

using std::vector;
using std::cin;
using std::cout;

long long MaxPairwiseProduct(const vector<int>& numbers) {
    long long result = 0;
    int n = numbers.size();
    for (int i = 0;i<n;++i) {
        for (int j = i+1;j<n;++j) {
            if (((long long)numbers[i] * numbers[j]) > result) {
                result = ((long long)(numbers[i]))*numbers[j];
            }
        }
    }
    return result;
}

long long MaxPairwiseProductFast(const vector<int>& numbers)
{int n = numbers.size();

    int max_index1 = -1;
    for(int i = 0;i<n;++i)
        if ((max_index1 == -1) || (numbers[i] > numbers[max_index1]))
            max_index1 = i;

    int max_index2 = -1;
    for(int j = 0;j<n;++j)
        if ((j !=max_index1) && (max_index2 == -1) || (numbers[j] > numbers[max_index1]))
            max_index2 = j;
    cout <<max_index1 << ' '<<max_index2 <<"\n";
}

int main() {
    while (true) {
        int n = rand() % 4 + 2;
        cout << n << "\n";
        vector<int>a;
        for (int i = 0;i<n;++i) {
            a.push_back(rand()% 10);
        }
        for(int i=0 ; i<n ; ++i) {
            cout <<a[i]<< ' ';
        }
        cout <<"\n";
        long long res1 = MaxPairwiseProduct(a);
        long long res2 = MaxPairwiseProductFast(a);
        if (res1 !=res2) {
            cout<< "wrong answer: "<< res1 << ' ' << res2 << "\n";
            break;
        }
        else {
            cout << "OK\n";
        }
    }
    int n;
    cin >> n;
    vector<int> numbers(n);
    for (int i=0;i<n; ++i) {
        cin >> numbers[i];
    }
    long long result = MaxPairwiseProductFast(numbers);
    cout << result << "\n";
    return 0;
}