diff --git a/range_queries/persistent_segment_tree_with_lazy_propagation.cpp b/range_queries/persistent_segment_tree_with_lazy_propagation.cpp
index f002345cd..47ed5922a 100644
--- a/range_queries/persistent_segment_tree_with_lazy_propagation.cpp
+++ b/range_queries/persistent_segment_tree_with_lazy_propagation.cpp
@@ -5,8 +5,7 @@
 // query -> range sum
 class perSegTree {
 private:
-    class Node {
-    public:
+    struct Node {
         Node *left;
         Node *right;
         int64_t val, prop;
@@ -20,8 +19,10 @@ private:
 
     int n; // number of elements in the segment tree
     std::vector<Node *> ptrs; // ptrs[i] holds a root pointer to the segment tree after the ith update
+    std::vector<int> vec;
+
     Node *newKid(Node *curr) {
-        Node *newNode = new Node();
+        Node *newNode = new Node;
         *newNode = *curr;
         return newNode;
     }
@@ -41,14 +42,14 @@ private:
         curr->prop = 0;
     }
 
-    void construct(int i, int j, std::vector<int> &vec, Node *&curr) {
-        curr = new Node();
+    void construct(int i, int j, Node *&curr) {
+        curr = new Node;
         if (i == j) {
             curr->val = vec[i];
         } else {
             int mid = i + (j - i) / 2;
-            construct(i, mid, vec, curr->left);
-            construct(mid + 1, j, vec, curr->right);
+            construct(i, mid, curr->left);
+            construct(mid + 1, j, curr->right);
             curr->val = curr->left->val + curr->right->val;
         }
     }
@@ -65,7 +66,7 @@ private:
         if (i > r || j < l) {
             return curr;
         }
-        Node *newNode = new Node();
+        Node *newNode = new Node;
         int mid = i + (j - i) / 2;
         newNode->left = update(i, mid, l, r, value, curr->left);
         newNode->right = update(mid + 1, j, l, r, value, curr->right);
@@ -86,7 +87,7 @@ private:
         return query(i, mid, l, r, curr->left) + query(mid + 1, j, l, r, curr->right);
     }
 
-    void clear(Node *&curr, int version) {
+    /*void clear(Node *&curr, int version) {
         if (!curr || curr->version != version) {
             return;
         }
@@ -94,48 +95,47 @@ private:
         clear(curr->right, version);
         delete curr;
     }
-
+    */ // for deallocation , version is passed to delete the current node iff its version = passed version
+    // that is, this node was created when the segment tree, whose version = this node's version, was created
+    // this is done to delete the segment trees top down version by version
 public:
     perSegTree() {
         n = 0;
     }
 
-    void construct(std::vector<int> &vec) // the segment tree will be built from the values in "vec", "vec" is 0 indexed
+    void construct(std::vector<int> vec) // the segment tree will be built from the values in "vec", "vec" is 0 indexed
     {
         if (vec.empty()) {
             return;
         }
         n = vec.size();
+        this->vec = vec;
         Node *root = nullptr;
-        construct(0, n - 1, vec, root);
+        construct(0, n - 1, root);
         ptrs.push_back(root);
     }
 
-    void update(int l, int r,
-                int value) // all elements from index "l" to index "r" would by updated by "value", "l" and "r" are 0 indexed
+    void update(int l, int r, int value) // all elements from index "l" to index "r" would by updated by "value", "l" and "r" are 0 indexed
     {
         ptrs.push_back(update(0, n - 1, l, r, value,
                               ptrs[ptrs.size() - 1])); // saving the root pointer to the new segment tree
     }
 
-    int64_t query(int l, int r,
-                  int version) // querying the range from "l" to "r" in a segment tree after "version" updates, "l" and "r" are 0 indexed
+    int64_t query(int l, int r, int version) // querying the range from "l" to "r" in a segment tree after "version" updates, "l" and "r" are 0 indexed
     {
         return query(0, n - 1, l, r, ptrs[version]);
     }
 
-    void clear() {
-        for (int i = (int) ptrs.size() - 1; i >= 0; --i) {
-            clear(ptrs[i],
-                  i); // every segment tree clears its nodes (nodes that were created when this segment tree was created)
+    /*void clear() {
+        for (int i = static_cast<int>(ptrs.size()) - 1; i >= 0; --i) {
+            clear(ptrs[i],i); // every segment tree clears its nodes (nodes that were created when this segment tree was created)
         }
         while (!ptrs.empty()) {
             ptrs.pop_back();
         }
-    }
+    }*/
 
-    int
-    size() // returns the number of segment trees (versions) , the number of updates done so far = returned value - 1 ,because one of the trees is the original segment tree
+    int size() // returns the number of segment trees (versions) , the number of updates done so far = returned value - 1 ,because one of the trees is the original segment tree
     {
         return ptrs.size();
     }
@@ -178,5 +178,4 @@ int main() {
     std::cout << "Number of segment trees (versions) now = " << tree.size() << '\n';
     std::cout << "Querying range sum on version 0 from index 3 to 5 = 11-2+7 = " << tree.query(3, 5, 0) << '\n';
     std::cout << "Querying range sum on version 1 from index 3 to 5 = 4-9+0 = " << tree.query(3, 5, 1) << '\n';
-    tree.clear();
 }
\ No newline at end of file