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/* | |
best time O(n log2 n) | |
worst time O(n log2 n) | |
*/ | |
package main | |
import ( | |
"fmt" | |
) |
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package main | |
// worst n^2 | |
// best n | |
import ( | |
"fmt" | |
) | |
func main() { | |
arr := []int{2,5,4,-8,9,1} |
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=begin | |
O(n + k) | |
=end | |
def countSort arr | |
countArr = [] | |
resultArr = Array.new(arr.length) | |
max = arr.max |
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def fib_rec (number) | |
if number == 0 | |
return number | |
elsif (number == 1) || (number == 2) | |
return 1 | |
end | |
fib_rec(number - 1) + fib_rec(number - 2) | |
end | |
def fib_non_rec (number) |
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# Set cover problem | |
states = ['mt', 'wa', 'or', 'id', 'nv', 'ut', 'ca', 'az'].uniq | |
station = {} | |
station["kone"] = ['id', 'nv', 'ut'].uniq | |
station["ktwo"] = ['mt', 'wa', 'id'].uniq | |
station["kthree"] = ['or', 'nv', 'ca'].uniq | |
station["kfour"] = ['nv', 'ut'].uniq | |
station["kfive"] = ['ca', 'az'].uniq |
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def sum_digits digit | |
if digit < 10 | |
digit | |
else | |
(digit % 10) + (digit / 10).to_f | |
end | |
end | |
def validate number | |
number = number.to_s.reverse.to_i |
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fib = 9 | |
def BinetFib number | |
phi = ((1 + Math.sqrt(5)) / 2) #or 1.6180339887 | |
divid = phi**number | |
divider = Math.sqrt(5) | |
(divid / divider).round | |
end | |
puts BinetFib(fib); |
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graph = {} | |
graph['start'] = Hash.new | |
graph['start']['a'] = 6 | |
graph['start']['b'] = 2 | |
graph['a'] = Hash.new | |
graph['a']['fin'] = 1 | |
graph['b'] = Hash.new | |
graph['b']['a'] = 3 | |
graph['b']['fin'] = 5 |
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# O(|V|+|E|) | |
graph = Hash.new | |
graph["you"] = ["alice", "bob", "claire"] | |
graph["bob"] = ["anuj", "peggy"] | |
graph["alice"] = ["peggy"] | |
graph["claire"] = ["thom", "jonny"] | |
graph["anuj"] = [] | |
graph["peggy"] = [] | |
graph["thom"] = [] |
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=begin | |
Worst time: O(n2) if choose bad pivot element | |
Approximate time: O(n log n) | |
=end | |
def quicksort array | |
if array.length < 2 | |
array | |
else | |
pivot = array[rand(array.length)] |