Create 3116-kth-smallest-amount-with-single-denomination-combination.js

Author: everthis

3116-kth-smallest-amount-with-single-denomination-combination.js

@@ -0,0 +1,59 @@
+function calcLcm(a, b) {
+  let p = a * b
+
+  let t = 0
+  while (b) {
+    t = b
+    b = a % b
+    a = t
+  }
+
+  return p / a
+}
+
+/**
+ * @param {number[]} coins
+ * @param {number} k
+ * @return {number}
+ */
+var findKthSmallest = function (coins, k) {
+  let n = coins.length
+
+  let cnt = 0
+  let lcm = 1
+  let sgn = -1
+  let cur = 0
+  let res = 0
+
+  let l = 1
+  let r = 50000000000
+
+  while (l <= r) {
+    cur = Math.floor((l + r) / 2)
+    cnt = 0
+    bt(0)
+
+    if (cnt >= k) {
+      res = cur
+      r = cur - 1
+    } else {
+      l = cur + 1
+    }
+  }
+
+  return res
+  
+  function bt(i) {
+    let bak = lcm
+    lcm = calcLcm(lcm, coins[i])
+    sgn = -sgn
+    cnt += sgn * Math.floor(cur / lcm)
+
+    ++i
+    if (i < n) bt(i)
+
+    lcm = bak
+    sgn = -sgn
+    if (i < n) bt(i)
+  }
+}