#include <iostream>
#include <conio.h>
using namespace std;
const int n = 15, need = 20;
int main()
{
int ar[n];
for(int i = 0; i < n; i++)
cin >> ar[i];
int res = 0;
for(int len = 20; len >= 0; len--)
{
int temp = res | (1 << len);
if(temp < n && ar[temp] <= need)
res = temp;
}
if(ar[res] != need)
cout << "No such number";
else
cout << res;
getch();
}
Следующий вариант
#include <iostream>
using namespace std;
const int n=15;
int binsearch(int a[], int nkey);
void sort (int []);
int main()
{
int a[n], i, k=0;
cout<<"enter "<<n<<" elements: ";
for (i=0; i<n; i++)
cin>>a[i];
sort (a);
cout<<"Otsortirovannij: ";
for (i=0; i<n; i++)
cout<<a[i]<<" ";
k=binsearch (a,20);
if (k==-1)
cout<<"no this number\n";
else
cout<<"position: "<<k<<endl;
return 0;
}
void sort (int mas[])
{
int i, j, buf;
for (i=0; i<n; i++)
for (j=n-1; j>i; j--)
if (mas[j-1]>mas[j])
{
buf=mas[j];
mas[j]=mas[j-1];
mas[j-1]=buf;
}
}
int binsearch(int mas[], int nkey)
{
int i = 0, k = n - 1;
while(i <= k)
{
int j = (i + k) / 2;
if (mas[j] == nkey)
return j; /* элемент найден */
if (mas[j] < nkey)
i = j + 1;
else
k = j - 1;
}
return -1; /* элемента нет */
}