// promisify(f, true) to get array of results
function promisify(f, manyArgs = false) {
  return function (...args) {
    return new Promise((resolve, reject) => {
      function callback(err, ...results) { // our custom callback for f
        if (err) {
          reject(err);
        } else {
          // resolve with all callback results if manyArgs is specified
          resolve(manyArgs ? results : results[0]);
        }
      }

      args.push(callback);

      f.call(this, ...args);
    });
  };
}

// usage:
f = promisify(f, true);
f(...).then(arrayOfResults => ..., err => ...);

const head = arr => (arr && arr.length ? arr[0] : undefined);

head([1, 2, 3]); // 1
head([]); // undefined
head(null); // undefined
head(undefined); // undefined

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    for(let i = 0; i < nums.length; i++) {
        for(let j = 0; j < nums.length; j++) {
            if(nums[i] + nums[j] === target && i !== j) {
                return [i, j]
            }
        }
    }
};

//QM Helper by Leif Messinger
//Groups numbers by number of bits and shows their binary representations.
//To be used on x.com
const minterms = prompt("Enter your minterms separated by commas").split(",").map(x => parseInt(x.trim()));
const maxNumBits = minterms.reduce(function(a, b) {
	return Math.max(a, Math.log2(b));
});
const bitGroups = [];
for(let i = 0; i < maxNumBits; ++i){
	bitGroups.push([]);
}
for(const minterm of minterms){
	let outputString = (minterm+" ");
	//Count the bits
	let count = 0;
	for (var i = maxNumBits; i >= 0; --i) {
		if((minterm >> i) & 1){
			++count;
			outputString += "1";
		}else{
			outputString += "0";
		}
	}
	bitGroups[count].push(outputString);
}
document.body.textContent = "";
document.body.style.setProperty("white-space", "pre");
for(const group of bitGroups){
	for(const outputString of group){
		document.body.textContent += outputString + "\r\n";
	}
}

const hammingDistance = (num1, num2) =>
  ((num1 ^ num2).toString(2).match(/1/g) || '').length;
  
hammingDistance(2, 3); // 1

// `arr` is an array
const clone = arr => arr.slice(0);

// Or
const clone = arr => [...arr];

// Or
const clone = arr => Array.from(arr);

// Or
const clone = arr => arr.map(x => x);

// Or
const clone = arr => JSON.parse(JSON.stringify(arr));

// Or
const clone = arr => arr.concat([]);