Time Limit Exceeded


  • 0
    D

    I am using a level order traversal which is a variant of O(n) algorithm. However I am getting Time Limit Exceeded 104 / 108 test cases passed. Could anyone please point out what might be wrong/optimized?

    class Solution {
        public int widthOfBinaryTree(TreeNode root) {
            if(root ==null){
                return 0;
            }
            
            Queue<TreeNode> queue = new LinkedList<>();
            queue.offer(root);
            queue.offer(new TreeNode(Integer.MAX_VALUE));
            List<Integer> list = new ArrayList<Integer>();
            
            int maxLevelCount = 0;
            int nullLevelCount =0;
    
            while(! queue.isEmpty()){
                TreeNode node = queue.poll();
                
                if(node==null){
                    nullLevelCount++;
                    list.add(null);
                    queue.offer(null);
                    queue.offer(null);
                }        
                else if(node.val == Integer.MAX_VALUE) {
                    if(nullLevelCount == list.size()){
                        break;
                    }                
                    
                    int leftIndex=0;
                    int rightIndex =0;
                    for(int i=0; i<list.size(); i++){
                        if(list.get(i)!=null){
                            leftIndex =i;
                            break;
                        }
                    }
                    
                    for(int i=list.size()-1; i>=0; i--){
                        if(list.get(i)!=null){
                            rightIndex =i;
                            break;
                        }
                    }
                    
                    int levelCount = rightIndex- leftIndex +1;
                    
                    if(levelCount > maxLevelCount){
                        maxLevelCount = levelCount;
                    }
                    
                    queue.offer(new TreeNode(Integer.MAX_VALUE));
                    list = new ArrayList<Integer>();
                    nullLevelCount = 0;
                    continue;
                }
                else {
                    list.add(node.val);
                    queue.offer(node.left);
                    queue.offer(node.right);
                }
            }
            
            return maxLevelCount;
        }
    }
    

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