Create 04 - Space Optimized | DP | Approach.cpp

Author: JawadSher

24 - Dynamic Programming Problems/06 - Max Sum without Adjacents/04 - Space Optimized | DP | Approach.cpp

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+// User function template for C++
+class Solution {
+  public:
+    // Function to find the maximum sum without adjacent elements using space-optimized DP
+    int solve(vector<int>& arr){
+        int n = arr.size();  // Get the size of the input array
+        
+        // Initialize the two variables to store the previous two results
+        int prev2 = 0;  // prev2 stores the maximum sum up to index i-2
+        int prev1 = arr[0];  // prev1 stores the maximum sum up to index i-1 (initially, it's the first element)
+        
+        // Iterate through the array starting from the second element
+        for(int i = 1; i < n; i++){
+            // Option 1: Include the current element arr[i]
+            int include = prev2 + arr[i];
+            
+            // Option 2: Exclude the current element arr[i]
+            int exclude = prev1;  // We just carry forward prev1 as it's the maximum sum up to the previous index
+            
+            // The result for the current index i is the maximum of include and exclude options
+            int ans = max(include, exclude);
+            
+            // Update prev2 and prev1 for the next iteration
+            prev2 = prev1;  // prev2 moves to prev1
+            prev1 = ans;    // prev1 stores the maximum sum for the current index
+        }
+        
+        // The final answer is stored in prev1 (which is the maximum sum for the entire array)
+        return prev1;
+    }
+    
+    // Main function to find the maximum sum
+    int findMaxSum(vector<int>& arr) {
+        
+        // Call the solve function and get the result
+        int sum = solve(arr);
+        
+        // Return the maximum sum
+        return sum;
+    }
+};