median.js

const Med = function() {
// assuming from 10 to 60 is the possibility
    this.range = Array(50).fill(0);
};

Med.prototype.next = function(num) {
    const num_index = num - 10; // from 10 ot 60 but using 0 - 50 as template
    this.range[num_index] += 1;
}
;
Med.prototype.median = function()  {
    const count = this.range.reduce((acc, cur) => acc + cur, 0);
    const mid_index = count / 2;
    // even or odd
    if (mid_index % 1.0 === 0) {
        return (conv_num(mid_index, this.range) + 
                conv_num(mid_index + 1, this.range)) / 2;
    }
    return conv_num(Math.ceil(mid_index), this.range);

};

const conv_num = function(num, range) {
    // count from the beginning of the range until it reaches mid_index
    let acc = 0;
    for (let i = 0; i < range.length; i++) {
        //console.log(acc, num, acc + range[i]);
        if (acc < num && num <= acc + range[i]) {
            return i + 10;
        }
        acc = acc + range[i];
    }
};

module.exports = Med;