Update 152.Maximum-Product-Subarray_DP.cpp

rhythmjayee · Sep 17, 2023 · 5603e40 · 5603e40
1 parent da12168
commit 5603e40
Showing 1 changed file with 17 additions and 10 deletions.
diff --git a/Dynamic_Programming/152.Maximum-Product-Subarray/152.Maximum-Product-Subarray_DP.cpp b/Dynamic_Programming/152.Maximum-Product-Subarray/152.Maximum-Product-Subarray_DP.cpp
@@ -1,20 +1,27 @@
+using LL = long long;
 class Solution {
 public:
     int maxProduct(vector<int>& nums) 
-    {        
-        int n = nums.size();
-        vector<long>dp1(n);
-        vector<long>dp2(n);
+    {
+        int n = nums.size();        
+        vector<LL>dp1(n);  // the max prod subarray ending at i
+        vector<LL>dp2(n);  // the min prod subarray ending at i
         dp1[0] = nums[0];
         dp2[0] = nums[0];
-        long ret =  nums[0];
+        LL ret = nums[0];
 
         for (int i=1; i<n; i++)
-        {            
-            dp1[i] = max(max(dp1[i-1]*(long)nums[i], dp2[i-1]*(long)nums[i]),(long)nums[i]);            
-            dp2[i] = min(min(dp1[i-1]*(long)nums[i], dp2[i-1]*(long)nums[i]),(long)nums[i]);            
-            ret = max(ret,dp1[i]);
+        {
+            dp1[i] = max(max(dp1[i-1] * nums[i], dp2[i-1] * nums[i]), (LL)nums[i]);
+            dp2[i] = min(min(dp1[i-1] * nums[i], dp2[i-1] * nums[i]), (LL)nums[i]);
+
+            dp1[i] = max((LL)INT_MIN, dp1[i]);
+            dp2[i] = max((LL)INT_MIN, dp2[i]);
+            dp1[i] = min((LL)INT_MAX, dp1[i]);
+            dp2[i] = min((LL)INT_MAX, dp2[i]);
+
+            ret = max(ret, dp1[i]);
         }
-        return ret;
+        return ret;        
     }
 };