Compute number of distinct values in an array.

Write a function

function solution(A);

that, given an array A consisting of N integers, returns the number of distinct values in array A.

For example, given array A consisting of six elements such that: A = 2 A = 1 A = 1 A = 2 A = 3 A = 1

the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.

Write an efficient algorithm for the following assumptions:

• N is an integer within the range [0..100,000];
• each element of array A is an integer within the range [−1,000,000..1,000,000].

Compute the number of intersections in a sequence of discs.

N voracious fish are moving along a river. Calculate how many fish are alive.

BinaryGap : Find longest sequence of zeros in binary representation

function solution(A) {
// write your code in JavaScript (Node.js 4.0.0)

if(A.length === 0) {
return 0;
} else if(A.length === 1) {
return 1;
}

A.sort(function(a, b) {
return a-b;
});

var i=0;
var counter = 1;

for(i=1; i<A.length; i++) {
if(A[i] !== A[i-1]) {
counter++;
}
}

return counter;
}