調試一個二分查找的例子

#include "stdafx.h"
#include <vector>
#include <iostream>

int bsearch(std::vector<int> vec , int x)
{
 int low ,high ;
 low = 0 ;
 high = vec.size() -1 ;

 int  mid =0 ;
 

 while(low <=high)
 {
  mid = (low +high ) /2;

  //if find x then break
  if(vec[mid] == x) break;
  //if x is greater than the mid value , assign the mid+1 to low
  else if (x > vec[mid])
   low = mid +1  ;
  else
   high = mid -1;

 }

 if(low <= high)
  return  mid;
 else
  return -1;
 

}

int main(int argc, char* argv[])
{
 std::vector<int> vec ;
 
 for(int i=0 ;i< 10;i++)
 {
  vec.push_back(i);
 }

 int ret = 0;
 ret = bsearch(vec ,5);
 std::cout<<"is 5 in vector "<< (ret== -1? "true":"false")<<"postion index:"<<ret <<std::endl;

 ret = bsearch(vec ,11);
 std::cout<<"is 11 in vector "<<(ret== -1? "true":"false")<<" position index:"<<ret <<std::endl;

 return 0;
}

說明：程序使用了vector 存儲數組，主要是方便取到數組長度