C++ 二分查找算法

C++ 二分查找算法

//Binary search 
//Programming by : Erfan Nasoori
//Mail : ketn68@yahoo.com
Date of send : 2009/2/1
#include <iostream>
#include <conio>
int binarysearch(int[],int,int);
int main()
{
 int sortedArray[100];
 int key,n,hold,F,L,k,G,i;
 cout<<"How many :";
 cin>>n;
 cout<<"Enter numbers :\n";
 for(int i=0;i<n;++i)
 {
  cout<<"number["<<(i+1)<<"] = ";
  cin>>sortedArray[i];
 }
 for(int l=1;l<=n-1;++l)
  for(int j=0;j<(n-l);++j)
  if(sortedArray[j]>sortedArray[j+1])
  {
	hold=sortedArray[j];
	sortedArray[j]=sortedArray[j+1];
	sortedArray[j+1]=hold;
  }
 cout<<"sorted numbers:";
 for( i=0;i<n;++i)
 cout<<sortedArray[i]<<'\t';
 cout<<"\nkey:";
 cin>>key;
 G=binarysearch(sortedArray,n,key);
 if(G == -1)
    cout<<"It didn't found!";
 else
    cout<<"\nIts index = "<<G<<endl;
 getch();
 return 0;
}   //end of main
//////////////////////////////////////////////////////////
int binarysearch(int sortedArray[], int n, int key)
{
 int first=0,last=n-1;
 while (first <= last)
 {
   int mid = (first + last) / 2;
   if (key > sortedArray[mid])
      first = mid + 1;
   else if (key < sortedArray[mid])
      last = mid - 1;
   else
      return mid;
 }
 return -1;
}