Binary Search

Compare	Represent
$\ge$	$lowerbound$
$>$	$\ge (x+1)$
$<$	$\ge (x)-1$
$\le$	$>x-1$

// >=
int index = lower_bound(X.begin(),X.end(),x)-X.begin();
// >
int index = lower_bound(X.begin(),X.end(),x+1)-X.begin();
// <
int index = lower_bound(X.begin(),X.end(),x)-1-X.begin();
//<=
int index = lower_bound(X.begin(),X.end()+1,x+1)-1-X.begin();