Add a Divide and Conquer version of the MaxSubArray problem.

src/algorithms/sets/maximum-subarray/dcMaximumSubarraySum.js

@@ -0,0 +1,33 @@
+/**
+ * Divide and Conquer solution.
+ * Complexity: O(n^2) in case if no memoization applied
+ *
+ * @param {Number[]} inputArray
+ * @return {Number[]}
+ */
+export default function dcMaximumSubarraySum(inputArray) {
+  /**
+   * We are going through the inputArray array and for each element we have two options:
+   * - to pick
+   * - not to pick
+   *
+   * Also keep in mind, that the maximum sub-array must be contiguous. It means if we picked
+   * the element, we need to continue picking the next elements or stop counting the max sum.
+   *
+   * @param {number} elementIndex - the index of the element we're deciding to pick or not
+   * @param {boolean} mustPick - to pick or not to pick the element
+   * @returns {number} - maximum subarray sum that we'll get
+   */
+  function solveRecursively(elementIndex, mustPick) {
+    if (elementIndex >= inputArray.length) {
+      return mustPick ? 0 : -Infinity;
+    }
+    return Math.max(
+      // Option #1: Pick the current element, and continue picking next one.
+      inputArray[elementIndex] + solveRecursively(elementIndex + 1, true),
+      // Option #2: Don't pick the current element.
+      mustPick ? 0 : solveRecursively(elementIndex + 1, false),
+    );
+  }
+  return solveRecursively(0, false);
+}