Feat: 152. Maximum Product Subarray

Author: HC-kang

maximum-product-subarray/HC-kang.ts

@@ -1,3 +1,26 @@
+/**
+ * https://leetcode.com/problems/maximum-product-subarray
+ * T.C. O(n)
+ * S.C. O(1)
+ * All numbers are integers, so multiplying two numbers cannot result in a smaller absolute value.
+ * It's important to pay attention to zeros and negative numbers.
+ */
 function maxProduct(nums: number[]): number {
-  return 0;
+  if (nums.length === 0) return 0;
+
+  let max = nums[0];
+  let min = nums[0];
+  let result = nums[0];
+
+  for (let i = 1; i < nums.length; i++) {
+    const num = nums[i];
+    if (num < 0) [max, min] = [min, max];
+
+    max = Math.max(num, max * num);
+    min = Math.min(num, min * num);
+
+    result = Math.max(result, max);
+  }
+
+  return result;
 }