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#include "hyperloglog.h"
 
#include <util/generic/buffer.h> 
#include <util/random/mersenne.h> 
#include <util/stream/buffer.h> 
 
#include <library/cpp/testing/unittest/registar.h>
 
#include <cmath> 
 
Y_UNIT_TEST_SUITE(THyperLogLog) {
    Y_UNIT_TEST(TestPrecision18) {
        TMersenne<ui64> rand; 
 
        auto counter = THyperLogLog::Create(18);
 
        static const std::pair<ui64, ui64> POINTS[] = { 
            {10, 10},
            {100, 100},
            {1000, 998},
            {10000, 9978},
            {100000, 99995},
            {1000000, 997017},
            {10000000, 9983891},
            {100000000, 100315572},
            {1000000000, 998791445},
            //1:37: {10000000000, 10015943904} 
        }; 
        ui64 unique = 0; 
        for (const auto& pnt : POINTS) { 
            while (unique < pnt.first) { 
                const auto val = rand(); 
                counter.Update(val); 
                ++unique; 
            } 
            const auto estimation = counter.Estimate(); 
            const auto delta = i64(estimation) - i64(unique); 
            const auto error = double(delta) / unique; 
            UNIT_ASSERT(std::abs(error) < 0.0032); 
            UNIT_ASSERT_EQUAL(estimation, pnt.second); 
        } 
        { 
            auto counter2 = THyperLogLog::Create(18);
            while (unique < 2000000000) { 
                const auto val = rand(); 
                counter2.Update(val); 
                ++unique; 
            } 
            const auto estimation = counter2.Estimate(); 
            UNIT_ASSERT_EQUAL(estimation, 1000013484); 
 
            counter.Merge(counter2); 
            UNIT_ASSERT_EQUAL(counter.Estimate(), 1998488794); 
        } 
 
        { 
            TBufferStream stream; 
            counter.Save(stream); 
            UNIT_ASSERT_EQUAL(stream.Buffer().Size(), 1 + (1 << 18)); 
 
            stream.Rewind(); 
            const auto copy = THyperLogLog::Load(stream);
 
            UNIT_ASSERT_EQUAL(counter.Estimate(), copy.Estimate()); 
        } 
    } 
}