Merge pull request #11 from ngthanhtrung23/master

Determinant - Gauss, Determinant - Kraut
Merge pull request #12 from ngthanhtrung23/master

Change base URL to avoid broken pages when update e-maxx-eng.github.io
Created src/geometry/length-of-segments-union.md
Merge pull request #1 from e-maxx-eng/master

Updating
updated src/index.md
Merge pull request #13 from ehlemur/master

Length of segments union
Add Fenwick tree article