parent
82f7a6c75a
commit
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@ -58,4 +58,31 @@ public class MinHeap {
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heapNodes[i] = heapNodes[j];
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heapNodes[j] = temp;
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}
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static int[] merge(int[][] array) {
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HeapNode[] heapNodes = new HeapNode[array.length];
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int resultingArraySize = 0;
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for (int i = 0; i < array.length; i++) {
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HeapNode node = new HeapNode(array[i][0], i);
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heapNodes[i] = node;
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resultingArraySize += array[i].length;
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}
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MinHeap minHeap = new MinHeap(heapNodes);
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int[] resultingArray = new int[resultingArraySize];
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for (int i = 0; i < resultingArraySize; i++) {
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HeapNode root = minHeap.getRootNode();
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resultingArray[i] = root.element;
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if (root.nextElementIndex < array[root.arrayIndex].length) {
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root.element = array[root.arrayIndex][root.nextElementIndex++];
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} else {
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root.element = Integer.MAX_VALUE;
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}
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minHeap.heapifyFromRoot();
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}
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return resultingArray;
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}
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}
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@ -1,40 +0,0 @@
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package com.baeldung.algorithms.minheapmerge;
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public class MinHeapMerge {
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static int populateHeapNodesAndDetermineResultingArrayLength(int[][] array, HeapNode[] heapNodes) {
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int resultSize = 0;
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for (int i = 0; i < array.length; i++) {
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HeapNode node = new HeapNode(array[i][0], i);
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heapNodes[i] = node;
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resultSize += array[i].length;
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}
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return resultSize;
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}
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static int[] createMinHeapAndMergeArrays(int[][] array, HeapNode[] heapNodes, int resultingArraySize) {
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MinHeap minHeap = new MinHeap(heapNodes);
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int[] resultingArray = new int[resultingArraySize];
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for (int i = 0; i < resultingArraySize; i++) {
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HeapNode root = minHeap.getRootNode();
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resultingArray[i] = root.element;
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if (root.nextElementIndex < array[root.arrayIndex].length) {
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root.element = array[root.arrayIndex][root.nextElementIndex++];
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} else {
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root.element = Integer.MAX_VALUE;
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}
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minHeap.heapifyFromRoot();
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}
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return resultingArray;
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}
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static int[] merge(int[][] array) {
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HeapNode[] heapNodes = new HeapNode[array.length];
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int resultingArraySize = populateHeapNodesAndDetermineResultingArrayLength(array, heapNodes);
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return createMinHeapAndMergeArrays(array, heapNodes, resultingArraySize);
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}
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}
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@ -1,39 +0,0 @@
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package com.baeldung.algorithms.minheapmerge;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.CoreMatchers.is;
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import static org.junit.Assert.assertThat;
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import org.junit.Test;
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public class MinHeapMergeUnitTest {
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private final int[][] inputArray = { { 0, 6 }, { 1, 5, 10, 100 }, { 2, 4, 200, 650 } };
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private final int[] expectedArray = { 0, 1, 2, 4, 5, 6, 10, 100, 200, 650 };
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@Test
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public void givenSortedArrays_whenMerged_thenShouldReturnASingleSortedarray() {
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int[] resultArray = MinHeapMerge.merge(inputArray);
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assertThat(resultArray.length, is(equalTo(10)));
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assertThat(resultArray, is(equalTo(expectedArray)));
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}
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@Test
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public void givenEmptyHeapNodesAndInputArray_whenPopulated_thenShouldPopulateAndReturnResultArrayLength() {
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int size = MinHeapMerge.populateHeapNodesAndDetermineResultingArrayLength(inputArray, new HeapNode[inputArray.length]);
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assertThat(size, is(equalTo(10)));
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}
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@Test
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public void givenArrayAndHeapNodesAndResultArraySize_whenMerged_thenShouldReturnASingleSortedarray() {
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HeapNode[] heapNodes = new HeapNode[inputArray.length];
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int size = MinHeapMerge.populateHeapNodesAndDetermineResultingArrayLength(inputArray, heapNodes);
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int[] resultArray = MinHeapMerge.createMinHeapAndMergeArrays(inputArray, heapNodes, size);
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assertThat(resultArray.length, is(equalTo(10)));
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assertThat(resultArray, is(equalTo(expectedArray)));
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}
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}
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@ -0,0 +1,22 @@
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package com.baeldung.algorithms.minheapmerge;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.CoreMatchers.is;
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import static org.junit.Assert.assertThat;
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import org.junit.Test;
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public class MinHeapUnitTest {
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private final int[][] inputArray = { { 0, 6 }, { 1, 5, 10, 100 }, { 2, 4, 200, 650 } };
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private final int[] expectedArray = { 0, 1, 2, 4, 5, 6, 10, 100, 200, 650 };
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@Test
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public void givenSortedArrays_whenMerged_thenShouldReturnASingleSortedarray() {
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int[] resultArray = MinHeap.merge(inputArray);
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assertThat(resultArray.length, is(equalTo(10)));
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assertThat(resultArray, is(equalTo(expectedArray)));
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}
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}
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