Create 1201-ugly-number-iii.js

Author: everthis

1201-ugly-number-iii.js

@@ -0,0 +1,30 @@
+/**
+ * @param {number} n
+ * @param {number} a
+ * @param {number} b
+ * @param {number} c
+ * @return {number}
+ */
+const nthUglyNumber = function(n, a, b, c) {
+  let lo = 1, hi = 2 * 1e9;
+  const { floor: f } = Math
+  let ab = a * b / gcd(a, b);
+  let bc = b * c / gcd(b, c);
+  let ac = a * c / gcd(a, c);
+  let abc = a * bc / gcd(a, bc);
+  while(lo < hi) {
+    let mid = lo + Math.floor((hi - lo) / 2);
+    if(valid(mid)) hi = mid;
+    else lo = mid + 1;
+  }
+  return lo;
+
+  function valid(mid) {
+    let res = f(mid / a) + f(mid / b) + f(mid / c) - f(mid / ab) - f(mid / bc) - f(mid / ac) + f(mid / abc)
+    return res >= n
+  }
+
+  function gcd(a, b) {
+    return b === 0 ? a : gcd(b, a % b)
+  }
+};