Create 3381-maximum-subarray-sum-with-length-divisible-by-k.js

Author: everthis

3381-maximum-subarray-sum-with-length-divisible-by-k.js

@@ -0,0 +1,36 @@
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+var maxSubarraySum = function (nums, k) {
+  const n = nums.length
+  let res = -Infinity
+  const pre_sum = new Array(n + 1).fill(0)
+
+  for (let i = 0; i < n; i++) {
+    pre_sum[i + 1] = pre_sum[i] + nums[i]
+  }
+
+  const groups = Array.from({ length: k }, (_, i) => [pre_sum[i]])
+
+  for (let i = k; i <= n; i++) {
+    const idx = i % k
+    groups[idx].push(pre_sum[i])
+  }
+
+  for (let i = 0; i < k; i++) {
+    const group = groups[i]
+    const mx_dp = new Array(group.length + 1).fill(-Infinity)
+
+    for (let j = group.length - 1; j >= 0; j--) {
+      mx_dp[j] = Math.max(mx_dp[j + 1], group[j])
+    }
+
+    for (let j = 0; j < group.length; j++) {
+      res = Math.max(res, mx_dp[j + 1] - group[j])
+    }
+  }
+
+  return res
+}