1 packagecom.datastruct;2

3 importjava.util.ArrayList;4 importjava.util.Arrays;5

6 public classBigHeap {7

8

9

10 /*

11 *交换堆中的两个元素12 */

13 private void swap(ArrayList heapList,int srcIndex,intdstIndex)14 {15 int tmp =heapList.get(srcIndex);16

17 heapList.set(srcIndex,heapList.get(dstIndex));18 heapList.set(dstIndex, tmp);19

20 }21

22 /*

23 *将指定元素的位置进行上移操作24 */

25 private void HeapUp(ArrayList heapList,intindex)26 {27

28 if(index > 1)29 {30 int parent = index / 2;31 int parentVal =heapList.get(parent).intValue();32 int indexVal =heapList.get(index).intValue();33

34 if(indexVal >parentVal)35 {36 swap(heapList,parent,index);37 HeapUp(heapList,parent);38 }39

40 }41 }42

43 /*

44 *将指定元素的位置进行下移操作45 */

46 private void HeapDown(ArrayList heapList,intindex)47 {48 int heapSize = heapList.size(); //这里进行了重复的计算,可以将作为形参传入，或者将该函数，写成非递归形式

49

50 if(index > heapSize - 1)51 {//节点不存在

52 return;53 }54

55 int child = index * 2; //左孩子节点

56

57 if(child > (heapSize - 2))58 {//当前节点为叶子节点，不能进行下移操作，直接返回59 //-2是由于最后一个元素已经是要删除的节点，不在计算范围之内

60 return;61 }62 else if(child < heapSize - 2)63 {//有两个孩子节点

64 if(heapList.get(child).intValue() < heapList.get(child + 1).intValue())65 {66 child++; //右孩子结点值大，作为新的父节点

67 }68 }69

70 if(heapList.get(child).intValue() >heapList.get(index).intValue())71 {//孩子节点的值大，进行下移

72 swap(heapList,child, index);73 HeapDown(heapList,child);//继续进行下移操作

74 }75

76 }77

78 /*

79 *向大顶堆中插入一个元素80 */

81 public void HeapInsert(ArrayList heapList,intvalue)82 {83 int heapSize =heapList.size();84

85 if(heapSize == 0)86 {//第一个元素不为堆中的元素，跳过

87 heapList.add(-100);88 }89

90 heapList.add(value);91 heapSize++; //添加新元素后，改变堆的大小

92

93 HeapUp(heapList,heapSize - 1);94 }95

96 /*

97 *从大顶堆中删除一个元素98 */

99 public void HeapDelete(ArrayList heapList,intvalue)100 {101 int index = 1,heapSize =heapList.size();102 for(; index < heapSize; index++)103 {104 if(heapList.get(index).intValue() ==value)105 {106 break;107 }108 }109

110 if (index >=heapSize)111 {//元素不存在

112 return;113 }114

115 heapList.set(index, heapList.get(heapSize-1)); //将最后一个叶子节点值赋值到当前节点

116 HeapDown(heapList,index);117

118 int parent = index / 2;119

120 if(parent > 0 && ( heapList.get(index).intValue() >(Integer)heapList.get(parent).intValue() ))121 {//如果下移操作后该元素大于父节点还要进行上移

122 HeapUp(heapList,index);123 }124

125 heapList.remove(heapSize - 1);126 }127

128 /*

129 *调整堆结构130 */

131 public void heapAdjust(ArrayListheapList,int index,intend)132 {133 int child = -1,heapSize =heapList.size();134

135 end = end > heapSize - 1 ? heapSize - 1 : end; //确保结束正确

136

137 while(index <= end / 2)138 {//只需调整非叶子节点

139 child = index * 2; //左孩子节点

140 if(child + 1 <= end && (heapList.get(child+1).intValue() >heapList.get(child).intValue()) )141 {142 child += 1; //右孩子节点值大右孩子节点上移

143 }144

145 if(heapList.get(child).intValue() >heapList.get(index).intValue())146 {147 swap(heapList, child, index);148 index =child;149 }150 else

151 {152 break;153 }154 }155 }156

157

158 /*

159 * 初始化时调整堆结构160 * 由于堆是完全二叉树结构，所以只有前一半节点是非叶子节点161 */

162 public void heapInitAdjust(ArrayListheapList)163 {164 int heapSize =heapList.size();165

166 for(int i = heapSize / 2; i > 0; i--)167 {168 heapAdjust(heapList, i, heapSize - 1);169 }170

171 }172

173 /*

174 * 堆排序175 * 将大顶堆堆顶元素和最后一个元素交换，调整剩下元素的对结构176 * 直到调整到最后一个元素就排好序177 */

178 public void heapSort(ArrayListheapList)179 {180 int heapSize =heapList.size();181

182 for(int i = heapSize - 1; i > 0; i--)183 {184 swap(heapList, 1, i); //交换堆顶和最后一个元素

185 heapAdjust(heapList, 1, i - 1);186 }187 }188

189 /*

190 * 打印堆元素191 */

192 public void PrintHeap(ArrayListheapList)193 {194 for(int i = 1; i < heapList.size(); i++)195 {196 System.out.print(heapList.get(i) + " ");197 }198

199 System.out.println();200 }201

202

203

204 public static voidmain(String args[])205 {206 ArrayList heapList = new ArrayList<>(Arrays.asList(null,1,3,4,5,8,2,7));207

208 BigHeap bigHeap = newBigHeap();209

210 bigHeap.heapInitAdjust(heapList);211 bigHeap.PrintHeap(heapList);212

213 bigHeap.HeapInsert(heapList, 6);214 bigHeap.PrintHeap(heapList);215

216 bigHeap.heapSort(heapList);217 bigHeap.PrintHeap(heapList);218 }219 }