折半法的简单应用

#include <iostream>

using namespace std;

int main()

{

int number;

cout<<"please input the length of array"<<endl;

cin>>number;

int *a=new int[number];

for (int i=0;i<number;i++)

{

cout<<endl;

printf("please input the %d element \n",i+1 );

cin>>a[i];

}

cout<<"please input the objective number"<<endl;

int number2;

cin>>number2;

int count=1;

int begin=0;

int end=number-1;

int start;

int index;

while (count<=number)

{

start=(begin+end)/2;

if (number2==a[start])

{

index=start+1;

break;

}

else if (number2>a[start])

{

begin=start+1;

start=(begin+end)/2;

count++;

}

else if (number2<a[start])

{

begin=0;

end=start-1;

start=(begin+end)/2;

count++;

}

}

if (count  > number)

cout<<"there don't exist the objective number in the array"<<endl;

else if (count<=number)

{

cout<<"the wanted number's index is ";

cout<<index<<endl;

}

return 0;

}