Algorithm to print all paths with a given sum in a binary tree

Question

The following is an interview question.

You are given a binary tree (not necessarily BST) in which each node contains a value. Design an algorithm t

Answer 1

Since we need the paths having sum == k . I assume worst case complexity can be O(total_paths_in_tree) .

So why not generate every path and check for the sum , anyways it is a tree having negative numbers and is not even a binary search tree .

    struct node{
      int val;
      node *left,*right;

      node(int vl)
      {
        val = vl;
        left = NULL;
        right = NULL;
      }
   };


   vector > all_paths;
   vector > gen_paths(node* root)
   {
       if(root==NULL)
       {
          return vector > ();
       }

       vector >    left_paths = gen_paths(root->left);
       vector >    right_paths = gen_paths(root->right);

       left_paths.push_back(vector ()); //empty path
       right_paths.push_back(vector ());

       vector > paths_here;
       paths_here.clear();


       for(int i=0;i vec;
              vec.clear();
              vec.insert(vec.end(), left_paths[i].begin(), left_paths[i].end());
             vec.push_back(root->val);
             vec.insert(vec.end(), right_paths[j].begin(), right_paths[j].end());
             paths_here.push_back(vec);
           }
        }

        all_paths.insert(all_paths.end(),paths_here.begin(),paths_here.end());

       vector > paths_to_extend;
       paths_to_extend.clear();

       for(int i=0;ival);
       }

       for(int i=0;ival);
       }

       return paths_to_extend;
    }

For generating paths I have generated all left paths and all right paths And added the left_paths + node->val + right_paths to all_paths at each node. And have sent the paths which can still be extended .i.e all paths from both sides + node .