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7.归并排序.c

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+#include<cstdio.h>
+#include<iostream.h>
+#include<algorithm.h>
+#include<cstring.h>
+using namespace std;
+ 
+void merge(int a[],int l,int r,int mid)
+{
+  int aux[r-l+1],i,j,k;
+  
+  for(k=l;k<=r;k++)
+  aux[k-l]=a[k];
+  
+  i=l;
+  j=mid+1;
+  for(k=l;k<=r;k++)
+  {
+   if(i>mid)
+   {
+    a[k]=aux[j-l];
+    j++;
+   }
+ else if(j>r)
+ {
+  a[k]=aux[i-l];
+  i++;
+   }
+ else if(aux[i-l]>aux[j-l])
+ {
+  a[k]=aux[j-l];
+  j++;
+  }
+ else
+ {
+  a[k]=aux[i-l];
+  i++;
+   }
+        
+   
+   } 
+ 
+}
+ 
+void merge_sort(int a[],int l,int r)
+{
+    if(l>=r)
+ return ;
+ 
+ int mid=(l+r)/2;
+ 
+ merge_sort(a,l,mid);
+ merge_sort(a,mid+1,r);
+ merge(a,l,r,mid); 
+ 
+}
+ 
+ 
+void mergesort(int a[],int l,int r)
+{
+ merge_sort(a,l,r-1);
+}
+ 
+int main()
+{
+ int a[105],n,i;
+ scanf("%d",&n);
+ 
+ for(i=0;i<n;i++)
+ scanf("%d",&a[i]);
+ 
+ mergesort(a,0,n);
+ 
+ for(i=0;i<n;i++)
+ printf("%d ",a[i]);
+ 
+ 
+ return 0;
+ }