refactor: feat: 53. Maximum Subarray

Author: gwbaik9717

maximum-subarray/gwbaik9717.js

@@ -1,18 +1,25 @@
 // Time complexity: O(n)
-// Space complexity: O(n)
+// Space complexity: O(1)
 
 /**
  * @param {number[]} nums
  * @return {number}
  */
 var maxSubArray = function (nums) {
   const n = nums.length;
-  const dp = Array.from({ length: n + 1 }, () => Number.MIN_SAFE_INTEGER);
-  dp[0] = 0;
+  const dp = [0, 0];
+
+  let answer = Number.MIN_SAFE_INTEGER;
 
   for (let i = 1; i <= n; i++) {
-    dp[i] = Math.max(dp[i - 1] + nums[i - 1], nums[i - 1]);
+    if (i % 2 !== 0) {
+      dp[1] = Math.max(dp[0] + nums[i - 1], nums[i - 1]);
+      answer = Math.max(answer, dp[1]);
+    } else {
+      dp[0] = Math.max(dp[1] + nums[i - 1], nums[i - 1]);
+      answer = Math.max(answer, dp[0]);
+    }
   }
 
-  return Math.max(...dp.slice(1));
+  return answer;
 };