Id,Name,Info
617,Merge Two Binary Trees, Recursive | No need to create node
461,Hamming distance, bit manipulation
566,reshap matrix,thinking tricky: minus 1 in the index id
500,Keyboard row, tricky point as List to array need a parameter so that return specific type arr not Obj[]
463,Island perimeter, only 1 island and no river in land
496, Next Greater Element I , in an array in sequence next greater item. could use stack but I use dumb HashMap O(n*m)
637, Average of Levels in Binary Tree, BFS using queue(Generate and Expand)