Create 1815-maximum-number-of-groups-getting-fresh-donuts.js

Author: everthis

1815-maximum-number-of-groups-getting-fresh-donuts.js

@@ -0,0 +1,53 @@
+/**
+ * @param {number} batchSize
+ * @param {number[]} groups
+ * @return {number}
+ */
+const maxHappyGroups = function (batchSize, groups) {
+  const arr = new Array(batchSize + 1).fill(0)
+  let result = 0
+  // reduce group to groups of size  group%n
+  for (let gSize of groups) {
+    arr[gSize % batchSize]++
+  }
+
+  // Only need 1 step
+  result += arr[0]
+  arr[0] = 0
+
+  // Only need 2 step
+  for (let i = 1; i < batchSize / 2; i++) {
+    let min = Math.min(arr[i], arr[batchSize - i])
+    arr[i] -= min
+    arr[batchSize - i] -= min
+    result += min
+  }
+  result += dfs(arr, 0, new Map())
+  return result
+}
+
+function dfs(arr, remain, cache) {
+  let n = arr.length - 1
+  const key = arr.join(',')
+  if (cache.has(key)) return cache.get(key)
+  let result = 0
+  // greedy and short cut when we can finish the current round
+  if (remain > 0 && arr[n - remain] > 0) {
+    arr[n - remain]--
+    result = dfs(arr, 0, cache)
+    arr[n - remain]++
+  } else {
+    for (let i = 1; i < arr.length; i++) {
+      if (arr[i] > 0) {
+        arr[i]--
+        result = Math.max(
+          result,
+          dfs(arr, (remain + i) % n, cache) + (remain == 0 ? 1 : 0)
+        )
+        arr[i]++
+      }
+    }
+  }
+  cache.set(key, result)
+  return result
+}