Leetcode 117

if(root == NULL) return;
        queue<TreeLinkNode *> que;
        que.push(root);
        while(!empty(que)){
            int lens = que.size();
            for(int i=0;i < lens-1;i++){
                TreeLinkNode *temp = que.front();
                que.pop();
                temp->next = que.front();
                if(temp->left) que.push(temp->left);
                if(temp->right) que.push(temp->right);
            }
            TreeLinkNode *temp2 = que.front();
            temp2->next = NULL;
            que.pop();
            if(temp2->left) que.push(temp2->left);
            if(temp2->right) que.push(temp2->right);
        }

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