euler154.js

var THT = 200000,
    exp_value = 12,
    Hash5 = [],
    Hash2 = [];

function getNumOfFactor5(num) {
  var count = 0,
      fact = 5;
  if (Hash5[num]) {
    return Hash5[num];
  }
  while (fact <= num) {
    count += ~~(num / fact);
    fact *= 5;
  }
  return Hash5[num] = count;
}
function getNumOfFactor2(numl) {
  var count = 0,
      fact = 2;
  if (Hash2[l]) {
    return Hash2[l];
  }
  while (fact <= l) {
    count += ~~(l / fact);
    fact *= 2;
  }
  return Hash2[l] = count;
}
var NUM_5FACT_THT = getNumOfFactor5(THT),
    NUM_2FACT_THT = getNumOfFactor2(THT),
    d = Date.now();
console.log('answer is : ' + function () {
  var sum5Fact , sum2Fact, a, b, c, count = 0;
  for (a = 0; a < THT / 3; a++) {
    for (b = a; b <= (THT - a) / 2; b++) {
      c = THT - a - b;
      sum5Fact = getNumOfFactor5(a) + getNumOfFactor5(b) + getNumOfFactor5(c);
      if (NUM_5FACT_THT - sum5Fact >= exp_value) {
        sum2Fact = getNumOfFactor2(a) + getNumOfFactor2(b) + getNumOfFactor2(c);
        if (NUM_2FACT_THT - sum2Fact >= exp_value) {
          if (a !== b && b !== c) {
            count += 6;
          } else {
            count += 3;
          }
        }
      }
    }
  }
  return count;
}());
console.log('time is : ', (Date.now() - d) / 1000);