HackerRank-CountPairs.js

function getValues(line) {
    return line.split(' ').map((i) => Number(i));
}

function processData(input) {
    var lines = input.split('\n');
    var inputValues = getValues(lines[0]);
    var array = getValues(lines[1]);
    
    fastest(inputValues[0], inputValues[1], array);
}

function fastest(N, K, array) {
    var set = array.reduce((obj, val) => { 
        obj[val] = true;
        return obj;
    }, {});
    var count = array.reduce((count, val) => {
        return set[val + K] ? count + 1 : count;
    }, 0);
    console.log(count);
    
    return count;
}

function fast(N, K, array) {
    var count = 0;
    var sorted = array.sort((a, b) => a - b);
    for (var j = 0; j < sorted.length; j++) {
       for (var i = j + 1; i < sorted.length; i++) {
           var diff = sorted[i] - sorted[j];
           if (diff === K) {
               count++;
               break;
           } else if(diff > K) {
               break;
           }
       } 
    }
    console.log(count);
}

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});