# Convert between graph representations.
[tag:code-golf][tag:graph-theory][tag:matrix]

## What?
Let's say I have this graph:
```
 1
 \
 \
2 3
 \ /
 \ /
 4
```
I can represent it in 2 ways:
- 1. A list of connected vertices. `[[1,3],[2,4],[3,4]]`
- 2. A boolean matrix which shows where edges are:
```
c |1 2 3 4
--|-------
1 |0 0 1 0
2 |0 0 0 1
3 |1 0 0 1
4 |0 1 1 0
----- or -----
[[0,0,1,0],[0,0,0,1],[1,0,0,1],[0,1,1,0]]
```

You code should take input in the form of 1 and output it as 2. The graph is not directed (aka undirected graph). You can also accept input which is 0-indexed.

## Test cases
```
[[1,2],[3,4]] -> [[0,1,0,0],[1,0,0,0],[0,0,0,1],[0,0,1,0]]
[[1,3],[2,4],[3,4]] -> [[0,0,1,0],[0,0,0,1],[1,0,0,1],[0,1,1,0]]
```