count tools (in topcoder)

ToolsBox.js

/* http://topcoder.g.hatena.ne.jp/eller/20091207 */

function countTools(need) {
  return need.join(' ').split(' ').reduce(function(sofar, v) {
    if (!sofar.hash[v]) sofar.count++;
    sofar.hash[v] = true;
    return sofar;
  }, {hash: {}, count: 0}).count;
}

console.log(countTools(
["SAW HAMMER SCREWDRIVER","SCREWDRIVER HAMMER KNIFE"]
), 4);


console.log(countTools(
["SAW"]
), 1);


console.log(countTools(
["SAW", "SAW"]
), 1);