Maximum Subarray

Author: casentino

maximum-subarray/casentino.ts

@@ -0,0 +1,30 @@
+function maxSubArray(nums: number[]): number {
+  function subSums(arr: number[], left: number, right: number) {
+    if (left === right) {
+      return nums[left];
+    }
+    const middle = Math.floor((left + right) / 2);
+
+    const leftMax = subSums(arr, left, middle);
+    const rightMax = subSums(arr, middle + 1, right);
+    let leftSum = 0;
+    let leftMaxSum = Number.NEGATIVE_INFINITY;
+    for (let i = middle; i >= left; i--) {
+      leftSum += arr[i];
+      if (leftMaxSum < leftSum) {
+        leftMaxSum = leftSum;
+      }
+    }
+    let rightSum = 0;
+    let rightMaxSum = Number.NEGATIVE_INFINITY;
+    for (let i = middle + 1; i <= right; i++) {
+      rightSum += arr[i];
+      if (rightMaxSum < rightSum) {
+        rightMaxSum = rightSum;
+      }
+    }
+
+    return Math.max(leftMaxSum + rightMaxSum, leftMax, rightMax);
+  }
+  return subSums(nums, 0, nums.length - 1);
+}