packagemedium;

importclasses.TreeNode;

publicclassLargestBSTSubtree {

publicintlargestBSTSubtree(TreeNoderoot) {

if(root ==null)return0;

if(isBST(root))returngetNodes(root);

returnMath.max(find(root.left),find(root.right));

}

intfind(TreeNoderoot){

if(isBST(root))returngetNodes(root);

returnMath.max(find(root.left),find(root.right));

}

intgetNodes(TreeNoderoot){

if(root ==null)return0;

returndfsCount(root);

}

intdfsCount(TreeNoderoot){

if(root ==null)return0;

returndfsCount(root.left) +dfsCount(root.right) +1;

}

booleanisBST(TreeNoderoot){

if(root ==null)returntrue;

returndfs(root,Long.MIN_VALUE,Long.MAX_VALUE);

}

booleandfs(TreeNoderoot,longmin,longmax){

if(root ==null)returntrue;

if(root.val <=min ||root.val >=max)returnfalse;

returndfs(root.left,min,root.val) &&dfs(root.right,root.val,max);

}

}

|349|[Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays/)|[Solution](../../blob/master/EASY/src/easy/IntersectionOfTwoArrays.java)| O(m+n)|O(min(m,n)) | Easy| Two Pointers, Binary Search

|346|[Moving Average from Data Stream](https://leetcode.com/problems/moving-average-from-data-stream/)|[Solution](../../blob/master/EASY/src/easy/MovingAveragefromDataStream.java)| O(1)|O(w)) | Easy| Queue

|339|[Nested List Weight Sum](https://leetcode.com/problems/nested-list-weight-sum/)|[Solution](../../blob/master/EASY/src/easy/NestedListWeightSum.java)| O(n)|O(h)) | Easy| DFS

|338|[Counting Bits](https://leetcode.com/problems/counting-bits/)|[Solution](../../blob/master/MEDIUM/src/medium/CountingBits.java)| O(n)|O(n)| Medium|

|338|[Counting Bits](https://leetcode.com/problems/counting-bits/)|[Solution](../../blob/master/MEDIUM/src/medium/CountingBits.java)| O(nlogn)|O(h)| Medium|

|333|[Largest BST Subtree](https://leetcode.com/problems/largest-bst-subtree/)|[Solution](../../blob/master/MEDIUM/src/medium/LargestBSTSubtree.java)| O(n)|O(n)| Medium|

|325|[Maximum Size Subarray Sum Equals k](https://leetcode.com/problems/maximum-size-subarray-sum-equals-k/)|[Solution] | O(n)|O(n) | Medium| HashMap

|314|[Binary Tree Vertical Order Traversal](https://leetcode.com/problems/binary-tree-vertical-order-traversal/)|[Solution](../../blob/master/MEDIUM/src/medium/BinaryTreeVerticalOrderTraversal.java)| O(n)|O(n) | Medium| HashMap, BFS

|311|[Sparse Matrix Multiplication](https://leetcode.com/problems/sparse-matrix-multiplication/)|[Solution](../../blob/master/MEDIUM/src/medium/SparseMatrixMultiplication.java)| O(m*n*l)|O(m*l)| Medium|