Trim a BST | 108. Convert Sorted Array to BST | 538. Convert BST to Greater Tree
Day1|704.BinarySearch|27.RemoveElement|35.SearchInsertPosition|34.FirstandLastPositionofElementinSortedArrayDay2|977.SquaresofaSortedArray|209.MinimumSizeSubarraySum|59.SpiralMatrixIIDay3|203.RemoveLi