findTheDifference, longestPalindrome, convertBST

gistfile1.txt

function charIncrement(item, obj) {
  item = item.split('');
  for (let i = 0; i < item.length; i++) {
    if (!obj[item[i]]) {
      obj[item[i]] = 1;
    } else {
      obj[item[i]]++;
    }
  }
  return obj;
}

function findTheDifference (s, t) {
  t = t.split('');
  let obj = {};
  charIncrement(s, obj);
  for (let i = 0; i < t.length; i++) {
    if (!obj[t[i]]) {
      return t[i];
    } else {
      obj[t[i]]--;
    }
  }
}
var longestPalindrome = function(s) {
    var obj = {};
    var result = 0;
    var singleChar = 0;
    charIncrement(s, obj);
    for (var prop in obj) {
        var even = obj[prop] % 2;
        if (even) {
            result += obj[prop] - 1;
            singleChar = 1;
        } else {
            result += obj[prop];
        }
    }
    return result + singleChar;
};

var convertBST = function(root) {
  var sum = 0;
  function nodeTrek(node) {
    if (!node) {
      return null;
    }
    nodeTrek(node.right);
    node.val += sum;
    sum = node.val;
    nodeTrek(node.left);
    return node;
  }
  return nodeTrek(root);
};