Create 3509-maximum-product-of-subsequences-with-an-alternating-sum-equal-to-k.js

Author: everthis

3509-maximum-product-of-subsequences-with-an-alternating-sum-equal-to-k.js

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+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @param {number} limit
+ * @return {number}
+ */
+var maxProduct = function(nums, k, limit) {
+    const MIN = -5000;
+    const dp = new Map();
+        const n = nums.length;
+
+        let sum = 0;
+        for (const x of nums) sum += x;
+
+        if (k > sum || k < -sum) return -1;
+
+ 
+        const ans = recursion(0, 0, 0, 0, k, n, nums, limit);
+        return (ans === MIN) ? -1 : ans;
+    function  recursion(pos, currSum, product, isOdd, k, n, nums, limit) {
+        if (pos === n) {
+            return (currSum === k && isOdd !== 0 && product <= limit ? product : MIN);
+        }
+
+        if (dp.has(pos) && dp.get(pos).has(currSum) && dp.get(pos).get(currSum).has(product) && dp.get(pos).get(currSum).get(product).has(isOdd)) {
+            return dp.get(pos).get(currSum).get(product).get(isOdd);
+        }
+
+        let ans = recursion(pos + 1, currSum, product, isOdd, k, n, nums, limit);
+        if (isOdd === 0) {
+            ans = Math.max(ans, recursion(pos + 1, currSum + nums[pos], nums[pos], 2, k, n, nums, limit));
+        }
+        if (isOdd === 1) {
+            ans = Math.max(ans, recursion(pos + 1, currSum + nums[pos], Math.min(product * nums[pos], limit + 1), 2, k, n, nums, limit));
+        }
+        if (isOdd === 2) {
+            ans = Math.max(ans, recursion(pos + 1, currSum - nums[pos], Math.min(product * nums[pos], limit + 1), 1, k, n, nums, limit));
+        }
+
+        if (!dp.has(pos)) {
+            dp.set(pos, new Map());
+        }
+        if (!dp.get(pos).has(currSum)) {
+            dp.get(pos).set(currSum, new Map());
+        }
+        if (!dp.get(pos).get(currSum).has(product)) {
+            dp.get(pos).get(currSum).set(product, new Map());
+        }
+        dp.get(pos).get(currSum).get(product).set(isOdd, ans);
+
+        return ans;
+    }
+};
+
+
+