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package bit;

import org.junit.Test;

import static org.hamcrest.CoreMatchers.is;

import static org.junit.Assert.assertThat;

public class BitMapTest {

TASK

O(1)으로 해당 데이터가 존재하는지 판단한다.

@Test

public void test() {

BitMap bitMap = new BitMap();

bitMap.store("1234567");

assertThat(bitMap.exist("1234567"), is(true));

assertThat(bitMap.exist("1234568"), is(false));

}

public class BitMap {

public int[] cache;

public BitMap() {

cache = new int[(10 * 1000 * 1000) / 32];

}

public void store(String data) {

int dataInt = Integer.parseInt(data);

int arrIndex = dataInt / 32;

int byteIndex = dataInt % 32;

cache[arrIndex] = cache[arrIndex] | (1 << byteIndex);

}

public boolean exist(String data) {

int dataInt = Integer.parseInt(data);

int arrIndex = dataInt / 32;

int byteIndex = dataInt % 32;

return (cache[arrIndex] & (1 << byteIndex)) != 0;

}