C++. Ëèíåéíûé è äâîè÷íûé ïîèñê ýëåìåíòîâ â ìàññèâå

Àëãîðèòì

1. Âûáðàòü ñðåäíèé ýëåìåíò A[c] è ñðàâíèòü ñ X.
2. Åñëè X = A[c], òî íàøëè (ñòîï).
3. Åñëè X < A[c], èñêàòü äàëüøå â ïåðâîé ïîëîâèíå.
4. Åñëè X > A[c], èñêàòü äàëüøå âî âòîðîé ïîëîâèíå.
    

Ðåàëèçàöèÿ

L = 0; R = N; // íà÷àëüíûé îòðåçîê
while ( L < R - 1)
{
	c = (L + R) / 2; // íàøëè ñåðåäèíó
	if ( X < A[c] )  // ñæàòèå îòðåçêà
	    R = c;
	else 
	    L = c;
}
if ( A[L] == X)
    cout << "A[" << L << "]=" << X;
else
    cout << "Not found";

L = 0; R = N - 1; 
while ( R >= L)
{
	c = (L + R) / 2; 
	if ( X == A[c] )
	{  
	    nX = c;
	    break;
	}
	if (X < A[c]) R = mid - 1;
	if (X > A[c]) L = mid + 1;
}
if ( nX < 0)
    cout << "Not found";
else
    cout << "A[" << nX << "]=" << X;