CODEWITHSUNDEEP
c++treestack
abhishek kr sahu
abhishek kr sahu

Reputation: 1

error: no matching member function for call to 'push'

Line 30: Char 11: error: no matching member function for call to 'push'
       s1.push(root);
       ~~~^~~~
/usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_stack.h:233:7: note: candidate function not viable: no known conversion from 'Node *' to 'const std::stack<TreeNode *, std::deque<TreeNode *, std::allocator<TreeNode *>>>::value_type' (aka 'TreeNode *const') for 1st argument
      push(const value_type& __x)
      ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/bits/stl_stack.h:238:7: note: candidate function not viable: no known conversion from 'Node *' to 'std::stack<TreeNode *, std::deque<TreeNode *, std::allocator<TreeNode *>>>::value_type' (aka 'TreeNode *') for 1st argument
      push(value_type&& __x)
      ^

public:
   vector<int> postorder(Node* root) {
       vector<int> v;
        if(root==NULL){
            return v;
        }
         stack<TreeNode *> s1;
       stack<TreeNode *> s2;
       s1.push(root);
       while(!s1.empty()){
           TreeNode* f=s1.top();
           s1.pop();
           s2.push(f);
           
           for(int i=0;i<f->children.size();i++){
               if(f->children[i]){
                   s1.push(f->children[i]);
               }
           }
           
           
       }
       while(!s2.empty()){
           v.push_back(s2.top()->val);
           s2.pop()
       }
       return v;
   }
};```

Upvotes: 0

Views: 3617

Answers (1)

newbie
newbie

Reputation: 415

s1 is of type stack<TreeNode *>, which means that it can only push values of TreeNode * type.

But root is of type Node* , which is different than TreeNode *.

Even if these types are similar ( and maybe convertible), because the function's argument is not recognized as TreeNode * type, the function is not recognized as a whole, hence the error!

If you pay attention to the error message it is saying that the argument of the push function should either be const value_type& or value_type&&. which means either const TreeNode *& or TreeNode *&&!

root is of none of those types!

Upvotes: 2

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