Vanya and Students 3rd time around
Tag(s):

## Easy, math, 简单, 簡単

Problem
Editorial
Analytics

Vanya is extremely curious about the characteristics of her students. She has for each student of her class $3$ pieces of information, i.e. their Name, ID and Height. Today, she has decided to play another game with her class. So, the rules of the game are :

This game consists of many turns. In each turn Vanya randomly picks any $2$ students of her class. She then notes down on a piece of paper she has, the product of the heights of the $2$ students.

She considers each pair of students only and exactly once. That is if Vanya has already written on the piece of paper the product of heights of $2$ students $(i,j)$, then she will not write it again.

She continues this procedure until each distinct pair of students has been considered. That is, if there are $N$ students studying in Vanya's class, then all valid pairs $(i,j)$ shall be :

$\forall_{i=1}^{N-1} \forall_{j=i+1}^{N} (i,j)$

Two Pairs $(i,j)$ and $(k,l)$ are considered to be distinct if $(i \ne k)$ or $(i \ne l)$ or $(j \ne k)$ or $(j \ne l)$.

Now, she wonders what is the sum of all the numbers written on this paper. Can you help her out ?

Table : Students

Field Type
Name text
ID text
Height int

Name ID Height
Micro 12abcd 2
Vasya 13abcd 3
Rhezo 14abcd 4

26

### Constraints:

The number of students shall not exceed 20.

The height of each student shall lie between $1$ and $10$ inclusive.

The length of Name and ID of each student shall lie between $1$ and $20$ inclusive.

Explanation

For the sample,

The unique pairs of students are :

1.>(Micro, Vasya). Product=$(2 \times 3)$ = $6$.

2 .> (Micro, Rhezo). Product= $(2 \times 4)$ = $8$.

2 ,> (Vasya, Rhezo) . Product = $(3 \times 4)$ = $12$.

Thus, the answer = $6+8+12$=$26$.

Time Limit: 5 sec(s) for each input file.
Memory Limit: 256 MB
Source Limit: 1024 KB
Marking Scheme: Marks are awarded when all the testcases pass.
Allowed Languages: MySQL, PostgreSQL, MSSQL, Oracle_Db

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