language: Ruby (ruby-1.9.2)
date: 103 days 18 hours ago
link:
visibility: public 
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a4 = []
a7 = []
ans = []
 
def add (a4,a7,l,r)
sum4 = 0
sum7 = 0
(l..r).each { |i|
sum4 = sum4 + a4[i]
sum7 = sum7 + a7[i]
}
if(sum4 == sum7)
return 1
end
return 0
 
end
t = gets.to_i
len = 0
(1..t).each {
n = gets.to_i
(len+1..n).each {|i|
a4[i] = i.to_s.count('4')
a7[i] = i.to_s.count('7')
len = len + 1
}
 
count = 0
(1..n).each { |l|
(l..n).each{ |r|
if r > ans.length
count = count + add(a4,a7,l,r)
else
count = count + ans[r-1]
end
}
}
ans << count 
 
print "#{ans[n-1]}\n"
}