常用数据结构及算法C#实现
1.冒泡排序、选择排序、插入排序（三种简单非递归排序）
1 int[] waitSort = { 1,0, 12, 13, 14, 5, 6, 7, 8, 9, 10 }; 2 3 //冒泡排序 4 int length = waitSort.Length; 5 6 for (int i = 0; i < length; i++) 7 { 8 for (int j = i + 1; j < length; j++) 9 { 10 if (waitSort[j] > waitSort[i]) 11 { 12 int temp = waitSort[j]; 13 waitSort[j] = waitSort[i]; 14 waitSort[i] = temp; 15 } 16 } 17 } 18 19 //选择排序 20 int pos1; 21 for (int i = 0; i < length; i++) 22 { 23 pos1 = i; 24 for (int j = i + 1; j < length; j++) 25 { 26 if (waitSort[pos1] < waitSort[j]) 27 { 28 pos1 = j; 29 } 30 } 31 if (pos1 != i) 32 { 33 int temp = waitSort[pos1]; 34 waitSort[pos1] = waitSort[i]; 35 waitSort[i] = temp; 36 } 37 } 38 39 //插入排序 40 for (int i = 1; i < length; i++) 41 { 42 for (int k = i; k > 0; k--) 43 { 44 if (waitSort[k] > waitSort[k - 1]) 45 { 46 int temp = waitSort[k]; 47 waitSort[k] = waitSort[k - 1]; 48 waitSort[k - 1] = temp; 49 } 50 } 51 } 52 53 foreach (var i in waitSort) 54 { 55 Console.WriteLine(i); 56 } 57 Console.ReadKey();
2.快速排序
C#版：
1 static int[] a = { 2, 5, 8, 6, 3, 4, 7, 9, 1,20,12,15,7,20,2 }; 2 static void Main(string[] args) 3 { 4 QuickSort(0, a.Length - 1); 5 foreach (var t in a) 6 { 7 Console.WriteLine(t); 8 } 9 Console.ReadKey(); 10 } 11 12 static void QuickSort(int low,int high) 13 { 14 if (low < high) 15 { 16 int partition=Partition(low,high); 17 QuickSort(low, partition-1); 18 QuickSort(partition+1, high); 19 } 20 } 21 22 static int Partition(int low, int high) 23 { 24 int point = a[low]; 25 while (low < high) 26 { 27 while (a[high] <= point && low<high) 28 { 29 high--; 30 } 31 Swap(high, low); 32 while (a[low] >= point && low<high) 33 { 34 low++; 35 } 36 Swap(high, low); 37 } 38 return low; 39 } 40 41 static void Swap(int x, int y) 42 { 43 int temp = a[x]; 44 a[x] = a[y]; 45 a[y] = temp; 46 }
Java版：
package test.JavaProject; import org.junit.Test; public class QuickSort { @Test public void test(){ int[] num = {1,5,6,9,8,7,5,3,5,4,1,2,6}; Qsort(num,0,num.length-1); for(int n:num){ System.out.println(n); } } public void Qsort(int[] num ,int left,int right){ if(left<right){ int p = partition(num,left,right); Qsort(num,left,p-1); Qsort(num,p+1,right); } } public int partition(int[] num,int left,int right){ int pivot = num[left]; while(right>left){ while(left<right && num[right]>=pivot){ right--; } exchenge(num,left,right); while(left<right && num[left]<=pivot){ left++; } exchenge(num,left,right); } return left; } public void exchenge(int[] num,int m,int n){ int temp = num[m]; num[m]=num[n]; num[n]=temp; } }
3.二叉排序树
1 namespace BinarySortTree 2 { 3 class Node 4 { 5 public int Num { get; set; } 6 public Node LChild { get; set; } 7 public Node RChild { get; set; } 8 } 9 10 class BinarySortTree 11 { 12 public Node Root { get; set; } 13 public BinarySortTree() 14 { 15 Root = new Node(); 16 } 17 } 18 19 class Program 20 { 21 static void Main(string[] args) 22 { 23 int[] sort = { 2, 5, 8, 3, 9, 6, 1, 7, 4,2,2,2 }; 24 BinarySortTree bst = new BinarySortTree(); 25 bst.Root.Num = 2; 26 for (int i = 1; i < sort.Length; i++) 27 { 28 InsertBst(bst.Root, sort[i]); 29 } 30 DFS(bst.Root); 31 Console.ReadKey(); 32 } 33 34 static void InsertBst(Node parent,int num) 35 { 36 if (num <= parent.Num) 37 { 38 if (parent.LChild == null) 39 { 40 parent.LChild = new Node(); 41 parent.LChild.Num = num; 42 return; 43 } 44 else 45 { 46 InsertBst(parent.LChild, num); 47 } 48 } 49 else 50 { 51 if (parent.RChild == null) 52 { 53 parent.RChild = new Node(); 54 parent.RChild.Num = num; 55 return; 56 } 57 else 58 { 59 InsertBst(parent.RChild, num); 60 } 61 } 62 } 63 64 static void DFS(Node parent) 65 { 66 67 if (parent.LChild != null) 68 { 69 DFS(parent.LChild); 70 71 } 72 Console.WriteLine(parent.Num); 73 74 if (parent.RChild != null) 75 { 76 DFS(parent.RChild); 77 } 78 } 79 } 80 }
4.堆排
1 namespace HeapSort 2 { 3 class Program 4 { 5 static int[] a = new int[] { -1,1, 5, 9, 3, 7, 6, 4, 2, 8 }; 6 static void Main(string[] args) 7 { 8 HeapSort(a.Length-1); 9 } 10 11 static void HeapSort(int len) 12 { 13 //第一次调整得到最小堆，即k>2k+1 && k>2k 14 for (int i = len/2; i >= 1; i--) 15 { 16 Adjust(i, len); 17 } 18 19 //第二次先交换第一个节点和最后一个节点，使堆顶元素最小，然后调整 20 for (int i = len; i >= 2; i--) 21 { 22 Swap(1, i); 23 Adjust(1, i-1); 24 } 25 } 26 27 static void Swap(int m,int n) 28 { 29 int temp = a[m]; 30 a[m] = a[n]; 31 a[n] = temp; 32 } 33 34 static void Adjust(int parent,int len) 35 { 36 int l = 2 * parent; 37 int r = 2 * parent + 1; 38 int largest = parent; 39 //选出最大的节点，用于与父节点交换位置 40 if (l <=len && a[l] > a[largest]) 41 { 42 largest = l; 43 } 44 if (r<=len && a[r]>a[largest]) 45 { 46 largest = r; 47 } 48 //如果需要调整父节点，先交换然后调整交换节点与其孩子节点 49 if (largest != parent) 50 { 51 Swap(parent, largest); 52 Adjust(largest, len); 53 } 54 } 55 } 56 }
5.栈的实现
1 namespace 栈 2 { 3 public class MyStack 4 { 5 private int index = -1; 6 private int[] a = new int[100]; 7 8 public void Push(int num) 9 { 10 a[++index] = num; 11 } 12 13 public int? Pop() 14 { 15 if (index == -1) 16 { 17 return null; 18 } 19 return a[index--]; 20 } 21 } 22 } 23 24 namespace 栈 25 { 26 class Program 27 { 28 static void Main(string[] args) 29 { 30 MyStack stack = new MyStack(); 31 stack.Push(1); 32 stack.Push(2); 33 stack.Push(3); 34 stack.Push(4); 35 int? temp; 36 while ((temp = stack.Pop()) != null) 37 { 38 Console.WriteLine(temp); 39 } 40 41 stack.Push(4); 42 stack.Push(3); 43 stack.Push(2); 44 stack.Push(1); 45 while ((temp = stack.Pop()) != null) 46 { 47 Console.WriteLine(temp); 48 } 49 Console.ReadKey(); 50 } 51 } 52 }
6.List实现
namespace MyList { public class Node { public int Num{get;set;} public Node Next{get;set;} } public class MyList { public Node Head { get; set; } public int Length { get; set; } public MyList() { Head = new Node(); Head.Next = null; Length = 1; } public void Add(int num) { Node n = new Node(); n.Num = num; Node node = Head; while (node.Next != null) { node = node.Next; } node.Next = n; Length++; } public void Delete(int index) { Node n = Head; if (index == 0) { Head = n.Next; } else if(Length-1==index) { for (int i = 0; i < index - 1; i++) { n = n.Next; } n.Next = null; } else { for (int i = 0; i < index - 1; i++) { n = n.Next; } n.Next = n.Next.Next; } Length--; } public int this[int index] { get { Node n = Head; for (int i = 0; i < index; i++) { n = n.Next; } return n.Num; } set { Node n = Head; for (int i = 0; i < index; i++) { n = n.Next; } n.Num = value; } } } } namespace MyList { class Program { static void Main(string[] args) { MyList list = new MyList(); list.Head.Num = 1; list.Add(2); list.Add(3); list.Add(4); list.Add(5); list.Add(6); Console.WriteLine("链表长度："+list.Length); Node n = list.Head; Console.WriteLine(n.Num); while (n.Next != null) { n = n.Next; Console.WriteLine(n.Num); } Console.ReadKey(); } } }
7.DFS(深搜)/BFS(宽搜)
1 private static void DFS(XmlNode parent) 2 { 3 if (!parent.HasChildNodes) 4 { 5 return; 6 } 7 else if (parent.HasChildNodes) 8 { 9 for (int j = 0; j < parent.ChildNodes.Count; j++) 10 { 11 if (parent.ChildNodes[j].Name == "span") 12 { 13 list.Add(parent.ChildNodes[j]); 14 } 15 DFS(parent.ChildNodes[j]); 16 } 17 } 18 } 19 20 21 public static void BFS(XmlNode root) 22 { 23 queue.Enqueue(root); 24 while (queue.Count != 0) 25 { 26 XmlNode n = queue.Dequeue(); 27 if (n.Name == "span") 28 { 29 list.Add(n); 30 } 31 for (int i = 0; i < n.ChildNodes.Count; i++) 32 { 33 queue.Enqueue(n.ChildNodes[i]); 34 } 35 } 36 }
8.优先队列（堆实现）
1 namespace PriorityQueue 2 { 3 class Program 4 { 5 static List<int> list = new List<int>(); 6 static void Main(string[] args) 7 { 8 list.Add(-1); 9 10 EnQueue(1); 11 EnQueue(3); 12 EnQueue(2); 13 EnQueue(4); 14 EnQueue(5); 15 EnQueue(7); 16 17 18 Console.WriteLine(DeQueue()); 19 20 EnQueue(10); 21 EnQueue(8); 22 EnQueue(15); 23 24 int num = -1; 25 while ((num = DeQueue()) != -1) 26 { 27 Console.WriteLine(num); 28 } 29 Console.ReadKey(); 30 } 31 32 static void EnQueue(int num) 33 { 34 list.Add(num); 35 Adjust((list.Count-1)/2, list.Count-1); 36 } 37 38 static int DeQueue() 39 { 40 int len = list.Count-1; 41 if (len == 0) 42 { 43 return -1; 44 } 45 46 Swap(1, len); 47 int num = list[len]; 48 list.RemoveAt(len); 49 50 int len1 = list.Count - 1; 51 Adjust(1, len1); 52 return num; 53 } 54 55 static void Adjust(int parent, int len) 56 { 57 if (parent == 0) 58 { 59 return; 60 } 61 int l = 2 * parent; 62 int r = 2 * parent + 1; 63 int min = parent; 64 //选出最大的节点，用于与父节点交换位置 65 if (l <= len && list[l] > list[min]) 66 { 67 min = l; 68 } 69 if (r <= len && list[r] > list[min]) 70 { 71 min = r; 72 } 73 //如果需要调整父节点，先交换然后调整父节点的父节点 74 if (min != parent) 75 { 76 Swap(parent, min); 77 Adjust(parent/2, len); 78 } 79 } 80 81 static void Swap(int m, int n) 82 { 83 int temp = list[m]; 84 list[m] = list[n]; 85 list[n] = temp; 86 } 87 88 89 } 90 }
9.归并排序
C#版：
1 namespace MergeSort 2 { 3 class Program 4 { 5 static int[] a = new int[] { 1,2,2,2, 3, 5, 7, 9, 2, 4, 8, 6 ,12,33,44,11,22,33}; 6 static void Main(string[] args) 7 { 8 MergeSort(0, a.Length-1); 9 } 10 11 static void MergeSort(int first, int last) 12 { 13 if (first < last) 14 { 15 int mid = (first + last) / 2; 16 MergeSort(first, mid); 17 MergeSort(mid + 1, last); 18 Merge(first, mid, last); 19 } 20 } 21 22 static void Merge(int first, int mid, int last) 23 { 24 int[] temp = new int[last - first + 1]; 25 int l = first; 26 int r = mid + 1; 27 int index = 0; 28 29 while (l <= mid && r <= last) 30 { 31 if (a[l] > a[r]) 32 { 33 temp[index++] = a[l++]; 34 } 35 else 36 { 37 temp[index++] = a[r++]; 38 } 39 } 40 41 while (l <= mid) 42 { 43 temp[index++] = a[l++]; 44 } 45 while (r <= last) 46 { 47 temp[index++] = a[r++]; 48 } 49 50 index = 0; 51 while (first <= last) 52 { 53 a[first++] = temp[index++]; 54 } 55 } 56 } 57 }
Java版：
package test.JavaProject; import org.junit.Test; public class MergeSort { @Test public void test(){ int[] num = {1,5,6,9,8,7,5,3,5,4,1,2,6}; mergeSort(num,0,num.length-1); for(int n:num){ System.out.println(n); } } public void mergeSort(int[] num,int first,int last){ if(first<last){ int middle = (last+first)/2; mergeSort(num,first,middle); mergeSort(num,middle+1,last); merge(num,first,middle,last); } } public void merge(int[] num,int first,int mid,int last){ int[] temp = new int[last-first+1]; int l = first; int r = mid+1; int index=0; while(l<=mid && r<=last){ if(num[l]<num[r]){ temp[index++]=num[l++]; } else{ temp[index++]=num[r++]; } } while(l<=mid){ temp[index++]=num[l++]; } while(r<=last){ temp[index++]=num[r++]; } index=0; while(first<=last){ num[first++]=temp[index++]; } } }
10.二分查找
1 namespace BinarySearch 2 { 3 class Program 4 { 5 static int[] search = {1,2,3,4,5,6,7,8,9,10}; 6 static void Main(string[] args) 7 { 8 int target = BinarySearch(7); 9 Console.WriteLine("第"+target+"个数"); 10 Console.WriteLine(search[target]); 11 Console.ReadKey(); 12 } 13 14 static int BinarySearch(int num) 15 { 16 int low = 0; 17 int high = search.Length-1; 18 while (high >= low) 19 { 20 int middle = (low + high) / 2; 21 if (search[middle] == num) 22 { 23 return middle; 24 } 25 else if (search[middle] > num) 26 { 27 high = middle-1; 28 } 29 else 30 { 31 low = middle + 1; 32 } 33 } 34 return -1; 35 } 36 } 37 }