归并排序优化，快速排序

Author: tianqing.liang

07MergeSort-More/ArrayGenerator.dart

@@ -0,0 +1,21 @@
+import 'dart:math';
+
+class ArrayGenerator{
+
+  static List generateOrderedArray(int n){
+     List arr =  List.filled(n, true);
+     for(int i = 0;i<n;i++){
+       arr[i] =i;
+     }
+     return arr;
+  }
+
+  static List generateRandomArray(int n,int bound){
+    List arr = List.filled(n, true);
+    Random random = new Random();
+    for(int i = 0; i < n; i ++){
+      arr[i] = random.nextInt(bound);
+    }
+    return arr;
+  }
+}

07MergeSort-More/MergeSort.dart

@@ -0,0 +1,118 @@
+import 'ArrayGenerator.dart';
+import 'dart:math';
+
+/**
+ * 自底向上归并排序
+ */
+class MergeSort{
+
+  static sort(List arr){
+    _sortContent(arr,0,arr.length-1);
+  }
+
+  static sortBU(List arr){
+    List temp = List.filled(arr.length, true);
+    List.copyRange(temp,0,arr);
+    int n = arr.length;
+    // 遍历合并的区间长度
+    for(int sz = 1; sz < n; sz += sz){
+      // 遍历合并的两个区间的起始位置 i
+      // 合并 [i, i + sz - 1] 和 [i + sz, Math.min(i + sz + sz - 1, n - 1)]
+      for(int i = 0; i + sz < n; i += sz + sz)
+        if(arr[i + sz - 1].compareTo(arr[i + sz]) > 0)
+          _merge2(arr, i, i + sz - 1, [i + sz + sz - 1, n - 1].reduce(min), temp);
+    }
+  }
+
+  static sort2(List arr){
+    List temp = List.filled(arr.length, true);
+    List.copyRange(temp,0,arr);
+    _sortContent2(arr, 0, arr.length - 1, temp);
+  }
+
+  static _sortContent2(List arr,int left,int right,List temp){
+    if (left >= right)
+      return;
+
+    int mid =  ((right - left) / 2).toInt() + left;
+    _sortContent2(arr, left, mid, temp);
+    _sortContent2(arr, mid + 1, right, temp);
+
+    if(arr[mid].compareTo(arr[mid + 1]) > 0)
+      _merge2(arr, left, mid, right, temp);
+  }
+  static _merge2(List arr,int left,int mid,int right,List temp){
+     List.copyRange(temp, left, arr,left,right+1);
+     int i = left, j = mid + 1;
+
+     // 每轮循环为 arr[k] 赋值
+     for(int k = left; k <= right; k ++){
+       if(i > mid){
+         arr[k] = temp[j];
+         j ++;
+       }
+       else if(j > right){
+         arr[k] = temp[i];
+         i ++;
+       }
+       else if(temp[i].compareTo(temp[j]) <= 0){
+         arr[k] = temp[i];
+         i ++;
+       }
+       else{
+         arr[k] = temp[j];
+         j ++;
+       }
+     }
+  }
+
+
+
+  static _sortContent (List arr,int left,int right){
+    /**
+     * 当数组过小时，可以使用插入排序
+     */
+    if(left >= right){
+      return;
+    }
+    int mid = ((right-left)/2).toInt() +left;
+    _sortContent(arr, left, mid);
+    _sortContent(arr, mid+1, right);
+    //提前进行判断，少一步merge
+    if(arr[mid].compareTo(arr[mid+1])>0){
+      _merge(arr,left,mid,right);
+    }
+  }
+
+  static _merge(List arr,int l,int mid,int right){
+    List temp = List.filled(right+1-l, true);
+    List.copyRange(temp, 0, arr,l,right+1);
+    int i = l, j = mid + 1;
+
+    // 每轮循环为 arr[k] 赋值
+    for(int k = l; k <= right; k ++){
+      if(i > mid){
+        arr[k] = temp[j - l]; j ++;
+      }
+      else if(j > right){
+        arr[k] = temp[i - l]; i ++;
+      }
+      else if(temp[i - l].compareTo(temp[j - l]) <= 0){
+        arr[k] = temp[i - l]; i ++;
+      }
+      else{
+        arr[k] = temp[j - l]; j ++;
+      }
+    }
+  }
+}
+void main(){
+  int n = 100;
+//  List arr = ArrayGenerator.generateRandomArray(n, n);
+//  MergeSort.sort(arr);
+//  print(arr);
+  List arr2 = ArrayGenerator.generateRandomArray(n, n);
+  print(arr2);
+  MergeSort.sortBU(arr2);
+  print(arr2);
+}

07MergeSort/MergeSort.dart

@@ -10,13 +10,19 @@ class MergeSort{
   }
 
   static _sortContent (List arr,int left,int right){
+    /**
+     * 当数组过小时，可以使用插入排序
+     */
     if(left >= right){
       return;
     }
     int mid = ((right-left)/2).toInt() +left;
     _sortContent(arr, left, mid);
     _sortContent(arr, mid+1, right);
-    _merge(arr,left,mid,right);
+    //提前进行判断，少一步merge
+    if(arr[mid].compareTo(arr[mid+1])>0){
+      _merge(arr,left,mid,right);
+    }
   }
 
   static _merge(List arr,int l,int mid,int right){
@@ -43,7 +49,7 @@ class MergeSort{
   }
 }
 void main(){
-  int n = 100;
+  int n = 20;
   List arr = ArrayGenerator.generateRandomArray(n, n);
   MergeSort.sort(arr);
   print(arr);

08-QuickSort/ArrayGenerator.dart

@@ -0,0 +1,21 @@
+import 'dart:math';
+
+class ArrayGenerator{
+
+  static List generateOrderedArray(int n){
+     List arr =  List.filled(n, true);
+     for(int i = 0;i<n;i++){
+       arr[i] =i;
+     }
+     return arr;
+  }
+
+  static List generateRandomArray(int n,int bound){
+    List arr = List.filled(n, true);
+    Random random = new Random();
+    for(int i = 0; i < n; i ++){
+      arr[i] = random.nextInt(bound);
+    }
+    return arr;
+  }
+}

08-QuickSort/QuickSort.dart

@@ -0,0 +1,41 @@
+import 'ArrayGenerator.dart';
+class QuickSort{
+  _QuickSort(){
+  }
+  static sort(List arr){
+    _sortDetail(arr,0,arr.length-1);
+  }
+
+  static _sortDetail(List arr,int left,int right){
+    if(left >= right){
+      return;
+    }
+    int p = _partition(arr, left, right);
+    _sortDetail(arr, left, p-1);
+    _sortDetail(arr, p+1, right);
+  }
+
+  static int _partition(List arr,int left,int right){
+    int j =left;
+    for(var i = left+1;i<=right;i++){
+        if(arr[i].compareTo(arr[left])<0){
+          j++;
+          _swap(arr,i,j);
+        }
+    }
+    _swap(arr, left, j);
+    return j;
+  }
+  static _swap(List arr,int i,int j){
+      var t =arr[i];
+      arr[i] = arr[j];
+      arr[j] = t;
+  }
+}
+void main(){
+  int n  =10;
+  List arr2 = ArrayGenerator.generateRandomArray(n, n);
+  print(arr2);
+  QuickSort.sort(arr2);
+  print(arr2);
+}

README.md

@@ -1,12 +1,15 @@
 # AlgorithmAndDataArchitecture
 
 #### 介绍
-使用Dart语言编写一套算法与数据结构
+使用Dart语言编写 慕课网算法与数据结构[https://class.imooc.com/sale/datastructure]
 1. 线性搜索
 2. 选择排序
 3. 插入排序
 4. 栈，队列，循环队列
 5. 链表，链表实现栈，链表实现队列
 6. 递归
-7. 归并排序
+7. 归并排序,归并排序排序优化,自底向上排序
+8. 快速排序
 
+#### SDK版本
+1. 版本：2.12.3