摘要： Code link: https://leetcode.com/problems/check-completeness-of-a-binary-tree/ Constraint: In a complete binary tree, every level, except possibly the 阅读全文

摘要： Code link: https://leetcode.com/problems/is-graph-bipartite/ Constraint: graph.length == n 1 <= n <= 100 0 <= graph[u].length < n 0 <= graph[u][i] <= 阅读全文

摘要： Code link: Idea We can do a BSF against the tree with a queue. The key here is to ensure all the nodes within the same level are added to the same lis 阅读全文

摘要： Code link: https://leetcode.com/problems/kth-largest-element-in-an-array/ Constraint: 1 ⇐ k ⇐ nums.length ⇐ 104 -104 ⇐ nums[i] ⇐ 104 Idea With the hel 阅读全文

摘要： Code link: https://leetcode.com/problems/validate-binary-search-tree/ Constraint: The number of nodes in the tree is in the range [1, 104]. -231 ⇐ Nod 阅读全文

摘要： Code link: https://leetcode.com/problems/same-tree/ Recursive solution: class Solution { public boolean isSameTree(TreeNode p, TreeNode q) { if (p == 阅读全文

摘要： Code link: https://leetcode.com/problems/symmetric-tree/ Recursive solution class Solution { public boolean isSymmetric(TreeNode root) { if (root == n 阅读全文

摘要： Code link: https://leetcode.com/problems/balanced-binary-tree/ Constraint: The number of nodes in the tree is in the range [0, 5000]. This means we ca 阅读全文

摘要： Problem link: https://leetcode.com/problems/binary-tree-postorder-traversal/ Constraint: Idea: We could do it either in recursive or iterative way. Co 阅读全文

摘要： Problem link: https://leetcode.com/problems/binary-tree-preorder-traversal/ Ideas We could do it in either iterative or recursive way. Code Recursive 阅读全文