Difficulty:

A newly-discovered planet has a few continents with one or more countries in each continent. Countries within a continent have land borders with at least another country in the same continent, and no two countries from different continents have a land border. Given a matrix of land borders between countries, we would like to calculate how many continents there are.

The borders data for

`n`

countries is an`n X n`

matrix, where a value of`1`

at i-th row and j-th column means a direct land border between i-th and j-th countries, and`0`

means no border. The matrix is symmetric, and no country has a border with itself.Given the borders matrix, return the number of continents.

continents([ [ 0, 1, 0 ], [ 1, 0, 0 ], [ 0, 0, 0 ] ]);

2

- Hint #1