Add 归并排序

归并排序

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+//归并排序
+void copyArray(int source[], int dest[],int len,int first)  
+{  
+    int i;  
+    int j=first;  
+    for(i=0;i<len;i++)  
+    {  
+        dest[j] = source[i];  
+        j++;  
+    }  
+          
+} 
+//相邻两个有序子序列的归并函数，将a[low...mid]和a[mid+1...high]归并到T[LOW..high]中 
+void merge(int a[],int left,int right)  
+{  
+    int begin1 = left;  
+    int mid = (left+right)/2 ;  
+    int begin2 = mid+1;  
+    int k=0;  
+    int newArrayLen = right-left+1;  
+    int *b = (int*)malloc(newArrayLen*sizeof(int));  
+    while(begin1<=mid && begin2<=right)  
+    {  
+        if(a[begin1]<=a[begin2])  
+            b[k++] = a[begin1++];  
+        else  
+            b[k++] = a[begin2++];  
+    }  
+    while(begin1<=mid)  
+        b[k++] = a[begin1++];  
+    while(begin2<=right)  
+        b[k++] = a[begin2++];  
+    copyArray(b,a,newArrayLen,left);  
+    free(b);  
+}  
+//归并函数,将a[low...high]归并到T[low...high]中
+void mergeSort(int a[],int left,int right)  
+{  
+    int i;  
+    // 保证至少有两个元素  
+    if(left < right)  
+    {  
+        i = (left+right)/2;  
+        mergeSort(a,left,i);  
+        mergeSort(a,i+1,right);  
+        merge(a,left,right);  
+    }  
+} 
+void MergeSort(int a[],int n)
+{
+	mergeSort(a,0,n-1);
+}
+int main()
+{
+	int n;
+	cin>>n;
+	int *a=new int[n];
+	
+	for(int j=0;j<n;j++)
+		cin>>a[j];
+	MergeSort(a,n);
+	for(int i=0;i<n;i++)
+		cout<<a[i];
+	delete []a;
+	
+}