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  1. function f(...)
  2.  
  3. r={}for i,t in ipairs(...)do for _,v in ipairs(t)do if r[v] then r[v][#r[v]+1]=i else r[v]={i}end end end return r
  4.  
  5. end
  6.  
  7. function dump(array)
  8. 	for i,t in ipairs(array) do
  9. 		array[i] = '{' .. table.concat(array[i],',') .. '}'
  10. 	end
  11. 	return '{' .. table.concat(array,',') .. '}'
  12. end
  13.  
  14. print(dump(f({{4,3,6,1},{2,4},{3,2,1,5},{5,6,4},{7,7}})))
  15. print(dump(f({{4,6,7,3},{1,1,1},{2,1,4,5}})))
  16. print(dump(f({{1},{1},{},{1}})))
Success #stdin #stdout 0s 2832KB
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Standard input is empty
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{{1,3},{2,3},{1,3},{1,2,4},{3,4},{1,4},{5,5}}
{{2,2,2,3},{3},{1},{1,3},{3},{1},{1}}
{{1,2,4}}
https://ideone.com/2xVqAA
language:
Lua (luac 5.3.3)
created:
7 years ago
visibility:
public

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