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| 1 | +package LinkedList; |
| 2 | + |
| 3 | +import java.util.LinkedList; |
| 4 | + |
| 5 | +public class DesignHashSet705 { |
| 6 | + |
| 7 | + private int size; |
| 8 | + private LinkedList<Integer>[] bucketarray; |
| 9 | + private static final int DEFAULT_CAPACITY = 10; |
| 10 | + |
| 11 | + public DesignHashSet705() { |
| 12 | + initbucket(DEFAULT_CAPACITY); |
| 13 | + size = 0; |
| 14 | + } |
| 15 | + |
| 16 | + private void initbucket(int capacity) { |
| 17 | + bucketarray = new LinkedList[capacity]; |
| 18 | + for (int i = 0; i < bucketarray.length; i++) { |
| 19 | + bucketarray[i] = new LinkedList<Integer>(); |
| 20 | + } |
| 21 | + } |
| 22 | + |
| 23 | + public void add(int key) { |
| 24 | + int bucketlocation = hashFunction(key); |
| 25 | + int datalocation = getDataWithinBucket(bucketlocation, key); |
| 26 | + |
| 27 | + if (datalocation == -1) { |
| 28 | + // data was not present in bucket so let's add in hashset |
| 29 | + bucketarray[bucketlocation].add(key); |
| 30 | + size++; |
| 31 | + } |
| 32 | + |
| 33 | + double lambda = size * 1.0 / bucketarray.length; |
| 34 | + if (lambda > 0.75) |
| 35 | + rehash(); |
| 36 | + } |
| 37 | + |
| 38 | + private int hashFunction(Integer key) { |
| 39 | + int index = key.hashCode(); |
| 40 | + return Math.abs(index) % bucketarray.length; |
| 41 | + } |
| 42 | + |
| 43 | + private int getDataWithinBucket(int location, int key) { |
| 44 | + LinkedList<Integer> currentBucket = bucketarray[location]; |
| 45 | + int index = 0; |
| 46 | + for (Integer data : currentBucket) { |
| 47 | + if (data == key) |
| 48 | + return index; |
| 49 | + index++; |
| 50 | + } |
| 51 | + return -1; // if not found |
| 52 | + } |
| 53 | + |
| 54 | + private void rehash() { |
| 55 | + LinkedList<Integer>[] oldbucket = bucketarray; |
| 56 | + initbucket(oldbucket.length * 2); |
| 57 | + size = 0; |
| 58 | + |
| 59 | + for (int i = 0; i < oldbucket.length; i++) { |
| 60 | + for (Integer value : oldbucket[i]) { |
| 61 | + add(value); // call add method of our hashset |
| 62 | + } |
| 63 | + } |
| 64 | + } |
| 65 | + |
| 66 | + public void remove(int key) { |
| 67 | + int bucketlocation = hashFunction(key); |
| 68 | + int datalocation = getDataWithinBucket(bucketlocation, key); |
| 69 | + |
| 70 | + if (datalocation == -1) |
| 71 | + return; // if no data found |
| 72 | + else { |
| 73 | + bucketarray[bucketlocation].remove(datalocation); |
| 74 | + size--; |
| 75 | + } |
| 76 | + } |
| 77 | + |
| 78 | + public boolean contains(int key) { |
| 79 | + int bucketlocation = hashFunction(key); |
| 80 | + int datalocation = getDataWithinBucket(bucketlocation, key); |
| 81 | + |
| 82 | + if (datalocation == -1) |
| 83 | + return false; |
| 84 | + else |
| 85 | + return true; |
| 86 | + } |
| 87 | +} |
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