归并排序

MergeSort.java

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+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package sort;
+
+/**
+ *
+ * @author User
+ */
+public class MergeSort {
+    
+    private static  int[] aux;
+    public static void merge(int[] a,int low, int mid,int high){
+        int i=low;
+        int j=mid+1;
+       
+        for(int k=low;k<=high;k++){
+            aux[k]=a[k];
+        }
+        for(int k=low;k<=high;k++){
+            if(i>mid){
+                a[k]=aux[j++];
+                
+            }
+            else if(j>high){
+                a[k]=aux[i++];
+            }
+            else if(aux[j]<aux[i]){
+                a[k]=aux[j++];
+            }
+            else{
+                a[k]=aux[i++];
+            }
+        }
+    }
+    private static void sort(int[] a,int low,int high){
+        if(high<=low) return;
+        int mid=low+(high-low)/2;
+        sort(a,low,mid);
+        sort(a,mid+1,high);
+        merge(a,low,mid,high);
+    }
+    public void sort(int[] a){
+        int length=a.length;
+        aux=new int[length];
+        sort(a,0,a.length-1);
+    }
+    
+}