/*

Suppose we know that the array contains exactly one duplicated entry

and that duplicate appears exactly twice. Find the duplicated entry.

(For bonus points, ensure your solution has constant space and

time proportional to N)

5;0,1,2,3,0 ==> 0

20;0,1,10,3,2,4,5,7,6,8,11,9,15,12,13,4,16,18,17,14 ==> 4

*/

var expect = require('chai').expect;

// create a frequency map

// stop when freq < 1

function cool(s) {

var a = s.split(';')[1].split(',');

var m = {}

, i = 0, j = a.length;

while (i < j ) {

if ( m[ a[i] ] ) {

return a[i];

} else {

m[ a[i] ] = 1;

}

i += 1

}

return null;

}

describe('cool()', function(){

it('should be 0', function(){

expect( cool("5;0,1,2,3,0") ).to.equal('0');

});

it('should be 0', function(){

expect( cool("0;0,1,10,3,2,4,5,7,6,8,11,9,15,12,13,4,16,18,17,14") )

.to.equal('4');

});

});