Number of occurrence.
class Solution{
public:
/* if x is present in arr[] then returns the count
of occurrences of x, otherwise returns 0. */
int count(int arr[], int n, int x) {
int lb= lower_bound(arr,arr+n,x)-arr;
int ub=uper_bound(arr,arr+n,x)-arr-1;
return (ub-lb+1) ;
}
};