刷题打卡 －pxu

139. Word Break. Used recursion and memorization to handle it

# Add Two Numbers forgot to add the carry need to add () around the conditional operator ?:

# Add Two Numbers
forgot to add the carry
need to add () around the conditional operator ?:

#160. Intersection of Two Linked Lists
forgot to move the point when calculate the list len
forgot to handle the edge case

# Merge k Sorted Lists
for using priorityQueue:
  forgot the check the null node
for Divide and conquer using two way merge:
code could more precise. using while(right >0)

#101. Symmetric Tree
used recursion or iteration with two queues

#129. Sum Root to Leaf Numbers
check root by left and right node, check null of them
if(root.left == null && root.right == null){  

#653. Two Sum IV - Input is a BST. lots of mistakes!
forgot to check k==root.val case
forgot to check (curr.val != k - curr.val)
forgot to check missing return statement
forgot to check root has no leafs case

#572. Subtree of Another Tree
added wrong nodes into the queue, should be n1, n2 instead of curr q1.add(curr.left);
using recursion seems easier

#102. Binary Tree Level Order Traversal
if (levelCount == 0) should be check after if(levelCount> 0) check, instead of if/else case