chaoxu

:Namespace Problem1

⎕IO ⎕ML ⎕WX ⎕RL←1 0 0 1093457855

 adjacency←{
     a←(⍺[;1]⍳⍵)        ⍝ edge indexed by numbers
     mat←(2⍴(⍴⍺[;1]))⍴0 ⍝ create a empty matrix
     mat[↓a⍪⌽a]←1       ⍝ set adjacent edges to 1
     mat
 }