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In a science research lab, combining two nuclear chemicals produces a maximum energy that is the product of the energy of the two chemicals. The energy values of the chemicals can be negative or positive. The scientist wishes to calculate the sum of the energies of the two chemicals which produces maximum energy on reaction.

Write an algorithm to find the sum of energy of the two chemicals which produces maximum energy on reaction.

**Input**

The first line of the input consists of an integer - numrChem, representing the number of chemicals (N).

The second line consists of N space-separated integers- ener*0*, ener*1* ....... ener*N-1* representing the energies of the chemicals.

**Output**

Print an integer representing the sum of energy of the two chemicals which produces maximum energy on reaction

**Constraints**

- 0 <= numOfChem <= 10^6
- -10^6 <= eneri <= 10^6
- 0 <= i <= numOfChem

**Example**

**Input**

```
9-3 8-6-7 8 10
```

**Output:**

```
19
```

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An employee in an organization has begun working on N projects (numbered 0 to N-1). Each week he/she can work on a single module of one of the projects. The modules that are chosen on any two successive weeks should come from different projects. A project i can have at most Ci modules.

The modules of the projects are such that a module is completed in a week.

Write an algorithm to determine the number of weeks the employee can work on projects following the above-mentioned rules.

**Input**

The first line of the input consists of an integer - num, representing the number of projects (N).

The next line consists of N space-separated integers - projC0, projC1, projCN-1, representing the number of modules of the projects.

**Output**

Print an integer representing the maximum number of weeks the employee can work on the projects

**Constraints**

- 1 <= num <= 5*10^4
- 1 <= projCi <= 10^7
- ΣprojCi <= 10^5
- 0 <= i < num

**Example**

**Input:**

```
3
7 2 3
```

**Output:**

```
11
```

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**Question 2**

**Approach/intuition**

- If we analyse this test case given in the problem and try to understand the problem then the solution doesn't seem that hard.
- For the given test case
`7,2,3`

than an employee can work for a maximum of 11 weeks on the projects. If an employee starts his work with one that requires the highest number of weeks which is 7 week and also end with that week then we are able to get a maximum of 11 weeks. - So the solution always exits as sum_of_all_element if The difference between
`Maximum_Element-Other_Element<=1 || Sum_of_other_element >Maximum_Element`

. - If none of the conditions satisfies then the sum of other elements excluding maximum is less than the
`maximum_element`

then answer will going to be`Sum_Of_other_Element*2+1`

- We can easily calculate the sum using for loop
- Time Complexity: O(N)

**Pseudo Code**

```
for (int i = 0; i < n; i++)
{
cin >> a[i];
mx = max(a[i], mx);
sum += a[i];
}
sum -= mx;
if (sum >= mx || sum - mx == 1)
{
cout << sum + mx << "\n";
}
else
{
cout << (sum * 2) + 1 << "\n";
}
```

Entering edit mode

**Question 1**

**Approach**

- The question wants to ask the sum of the two largest elements in the given array.
- We can easily calculate that by sorting the array and counting the number of negative elements in array
- If the number of negative elements in the array is greater than 1 then there is the possibility that the product of two negative elements give the largest value.
- So if the number of negative elements is greater than 1 we can check
`max(a[0]*a[1],a[n-1]*a[n-2])`

- If maximum is from the starting we can print a[0]+a[1] else we can
`print a[n-1]+a[n-2]`

- Time complexity:
`O(NLogN)`

**Pseudo Code**

```
Take input of the array
cnt Number of negative elements
sort the array from 0 to n-1
let start=a[0]+a[1] and end =a[n-1]+a[n-2]
check maximum product
if(start>end)
print a[0]+a[1]
else
print arr[n-1]+arr[n-2]
```

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start = a[0]

a[1] and end = a[-1]a[-2]