Add solution #1994

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,675 LeetCode solutions in JavaScript
+# 1,676 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1529,6 +1529,7 @@
 1991|[Find the Middle Index in Array](./solutions/1991-find-the-middle-index-in-array.js)|Easy|
 1992|[Find All Groups of Farmland](./solutions/1992-find-all-groups-of-farmland.js)|Medium|
 1993|[Operations on Tree](./solutions/1993-operations-on-tree.js)|Medium|
+1994|[The Number of Good Subsets](./solutions/1994-the-number-of-good-subsets.js)|Hard|
 1996|[The Number of Weak Characters in the Game](./solutions/1996-the-number-of-weak-characters-in-the-game.js)|Medium|
 2000|[Reverse Prefix of Word](./solutions/2000-reverse-prefix-of-word.js)|Easy|
 2011|[Final Value of Variable After Performing Operations](./solutions/2011-final-value-of-variable-after-performing-operations.js)|Easy|

solutions/1994-the-number-of-good-subsets.js

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+/**
+ * 1994. The Number of Good Subsets
+ * https://leetcode.com/problems/the-number-of-good-subsets/
+ * Difficulty: Hard
+ *
+ * You are given an integer array nums. We call a subset of nums good if its product can be
+ * represented as a product of one or more distinct prime numbers.
+ *
+ * - For example, if nums = [1, 2, 3, 4]:
+ *   - [2, 3], [1, 2, 3], and [1, 3] are good subsets with products 6 = 2*3, 6 = 2*3, and 3 = 3
+ *     respectively.
+ *   - [1, 4] and [4] are not good subsets with products 4 = 2*2 and 4 = 2*2 respectively.
+ *
+ * Return the number of different good subsets in nums modulo 109 + 7.
+ *
+ * A subset of nums is any array that can be obtained by deleting some (possibly none or all)
+ * elements from nums. Two subsets are different if and only if the chosen indices to delete
+ * are different.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var numberOfGoodSubsets = function(nums) {
+  const MOD = 1e9 + 7;
+  const primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29];
+  const freq = new Array(31).fill(0);
+  for (const num of nums) {
+    freq[num]++;
+  }
+
+  const dp = new Array(1 << primes.length).fill(0);
+  dp[0] = 1;
+  for (let i = 0; i < freq[1]; i++) {
+    dp[0] = (dp[0] * 2) % MOD;
+  }
+
+  for (let num = 2; num <= 30; num++) {
+    if (freq[num] === 0) continue;
+    let mask = 0;
+    let valid = true;
+    for (let i = 0; i < primes.length; i++) {
+      let count = 0;
+      let temp = num;
+      while (temp % primes[i] === 0) {
+        count++;
+        temp /= primes[i];
+      }
+      if (count > 1) {
+        valid = false;
+        break;
+      }
+      if (count === 1) {
+        mask |= 1 << i;
+      }
+    }
+
+    if (!valid) continue;
+
+    const prev = dp.slice();
+    for (let j = 0; j < 1 << primes.length; j++) {
+      if ((j & mask) === 0) {
+        dp[j | mask] = (dp[j | mask] + prev[j] * freq[num]) % MOD;
+      }
+    }
+  }
+
+  let result = 0;
+  for (let i = 1; i < 1 << primes.length; i++) {
+    result = (result + dp[i]) % MOD;
+  }
+
+  return result;
+};