[강병준] Maximum Product Subarray

bangdori/152.js

@@ -0,0 +1,56 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxProduct = function (nums) {
+  const segments = splitByZero(nums);
+  let maxProduct = Number.NEGATIVE_INFINITY;
+
+  for (const segment of segments) {
+    const currentProduct = maxProductOfSegment(segment);
+    maxProduct = Math.max(maxProduct, currentProduct);
+  }
+
+  if (nums.includes(0)) maxProduct = Math.max(maxProduct, 0);
+
+  return maxProduct;
+};
+
+function splitByZero(nums) {
+  const result = [];
+  let current = [];
+
+  for (const num of nums) {
+    if (num === 0) {
+      result.push(current);
+      current = [];
+    } else {
+      current.push(num);
+    }
+  }
+
+  result.push(current);
+  return result.filter((array) => array.length > 0);
+}
+
+function maxProductOfSegment(nums) {
+  let maxProduct = Number.NEGATIVE_INFINITY;
+
+  let currentProduct = 1;
+  for (let i = 0; i < nums.length; i++) {
+    currentProduct *= nums[i];
+    maxProduct = Math.max(maxProduct, currentProduct);
+
+    if (currentProduct === 0) currentProduct = 1;
+  }
+
+  currentProduct = 1;
+  for (let i = nums.length - 1; i >= 0; i--) {
+    currentProduct *= nums[i];
+    maxProduct = Math.max(maxProduct, currentProduct);
+
+    if (currentProduct === 0) currentProduct = 1;
+  }
+
+  return maxProduct;
+}