Maximum Product Subarray

Author: sachuverma

Diff for: DSA Crack Sheet/README.md

@@ -23,6 +23,7 @@
 - [Rearrange array in alternating positive & negative items with O(1) extra space](https://www.geeksforgeeks.org/rearrange-array-alternating-positive-negative-items-o1-extra-space/ "view topic") - [Cpp Solution](./solutions/Rearrange%20array%20in%20alternating%20positive%20&%20negative%20items%20with%20O(1)%20extra%20space.cpp)
 - [Subarray with 0 sum](https://practice.geeksforgeeks.org/problems/subarray-with-0-sum-1587115621/1# "view question") - [Cpp Solution](./solutions/Subarray%20with%200%20sum.cpp)
 - [Factorials of large numbers](https://practice.geeksforgeeks.org/problems/factorials-of-large-numbers/0# "view question") - [Cpp Solution](./solutions/Factorials%20of%20large%20numbers.cpp)
+- [Maximum Product Subarray](https://practice.geeksforgeeks.org/problems/maximum-product-subarray3604/1 "view question") - [Cpp Solution](./solutions/Maximum%20Product%20Subarray.cpp)
 - []( "view question") - [Cpp Solution](./solutions/.cpp)
 
 <!-- - []( "view question") - [Cpp Solution](./solutions/) -->

Diff for: DSA Crack Sheet/solutions/Maximum Product Subarray.cpp

@@ -0,0 +1,50 @@
+/*
+Maximum Product Subarray
+========================
+
+Given an array Arr that contains N integers (may be positive, negative or zero). Find the product of the maximum product subarray.
+
+Example 1:
+Input:
+N = 5
+Arr[] = {6, -3, -10, 0, 2}
+Output: 180
+Explanation: Subarray with maximum product
+is  6, -3, -10 which gives product as 180.
+
+Example 2:
+Input:
+N = 6
+Arr[] = {2, 3, 4, 5, -1, 0}
+Output: 120
+Explanation: Subarray with maximum product
+is 2, 3, 4, 5 which gives product as 120.
+Your Task:
+You don't need to read input or print anything. Your task is to complete the function maxProduct() which takes the array of integers arr and n as parameters and returns an integer denoting the answer.
+Note: Use 64-bit integer data type to avoid overflow.
+
+Expected Time Complexity: O(N)
+Expected Auxiliary Space: O(1)
+
+Constraints:
+1 <= N <= 500
+-102 <= Arri <= 102
+*/
+
+long long maxProduct(int *nums, int n)
+{
+  long long min_here = nums[0], max_here = nums[0], ans = nums[0];
+
+  for (int i = 1; i < n; ++i)
+  {
+    if (nums[i] < 0)
+      swap(max_here, min_here);
+
+    max_here = max((long long)nums[i], max_here * nums[i]);
+    min_here = min((long long)nums[i], min_here * nums[i]);
+
+    ans = max(ans, max_here);
+  }
+
+  return ans;
+}