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#include <iostream> | |
#include <vector> | |
#include <unordered_map> | |
//using namespace std; | |
std::vector<int> find_sum(const std::vector<int> &list, int target_sum) // O(n) | |
{ | |
std::unordered_map<int, int> all_compl; | |
for(auto i : list) // O(n) | |
{ | |
auto it = all_compl.find(i); // find - O(1) | |
if (it != all_compl.end()) | |
return {it->first, it->second}; | |
int complementary = target_sum - i; | |
all_compl[complementary] = i; // append - O(1) | |
} | |
return {}; | |
} | |
int main() | |
{ | |
std::vector<int> list = {1,2,3,4,5,6}; | |
int target_sum = 10; | |
std::vector<int> answer = find_sum(list, target_sum); // O(n) | |
std::cout << "{"; | |
for (auto i: answer) | |
std::cout << i << " "; | |
std::cout << "}" << std::endl; | |
return 0; | |
} |
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module Main where | |
import qualified Data.Map as M | |
-- :set -package containers | |
list1 = [1,2,3,4,5,6] | |
targetSum1 = 10 | |
myFind :: (Ord a, Num a) => [a] -> a -> [a] | |
myFind list targetSum = myFind' Nothing list M.empty targetSum | |
-- myFind' is O(n * log n) | |
myFind' (Just a) _ _ tsum = [a, tsum-a] | |
myFind' _ [] _ tsum = [] | |
myFind' Nothing (x:xs) someMap tsum = myFind' element xs newSomeMap tsum | |
where | |
newSomeMap = (M.insert (tsum - x) x someMap) -- O(log n) | |
element = (M.lookup x someMap) -- O(log n) 😥 | |
-- А нужно было использовать пакет hashtables (а именно BasicHashTable) ! | |
main :: IO () | |
main = do | |
putStrLn $ show $ myFind list1 targetSum1 |
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