Binary Tree Right Side View | Leetcode Solution

if you know level order traversal then you also know the solution of this question. this question is same as level order traversal with little modification.

vector<int> rightSideView(TreeNode* root) {

        vector<int>mainans;
         queue<TreeNode*> q;
        if(root==NULL){
            return mainans;
        }
        q.push(root);
        q.push(NULL);
        TreeNode *ans,*ans1;
        while(!q.empty()){
              ans=q.front();
              q.pop();
            if(!q.empty())
                 ans1=q.front();
            else{
                break;
            }

            if(!ans){
                if(q.empty()){
                    break;
                }
                else{
                    q.push(NULL);
                    continue;
                }
            }

            if(!ans1 && ans){
                mainans.push_back(ans->val);
            }




           if(ans->left!=NULL && ans->right!=NULL){
                    q.push(ans->left);
                    q.push(ans->right);
            }
            if(ans->left!=NULL && ans->right==NULL){
                  q.push(ans->left);
            }
           if(ans->left==NULL && ans->right!=NULL){
                   q.push(ans->right);
            }
            if(ans->left==NULL && ans->right==NULL){
                continue;
            }
        }
        return mainans;
    }

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