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"Find the Weak Connected Component in the Directed Graph",
"Graph Valid Tree",
]
},
"Graph" : {
"nickname": "",
"property" : [
"x",
],
"problems" : [
"x",
]
},
"Binary tree" : {
"nickname": "二叉树",
"property" : [
"recursive, left, right",
"Binary Tree pre,in,post Traversal 都用到： DFS, Stack; divide && conquer（注意里面是return rst, 要懂得addAll）; recursive with helper"
"Preorder Traversal: 1. Divide and conquer; 2. 1 stack: streo curr.val; push right, push left; 3. recursive with helper",
"Postorder Traversal: 1. Divide left&&right, conquer (add left, right, curr) 2. Two Stack(巧妙的s1,s2关系)，最后output s2. 3. recursive with helper function",
"Inorder Traversal: 1. Divide and conquer; 2. 1 Stack: move all the way to left-down; add curr; move to right and push right; 3. Recursive with helper",
"Level Order Traversal: 1. Use queue, do bfs. 2. dfs: track with level number: each level add a new [] list in rst"
],
"problems" : [
"Binary Tree Paths",
"Binary Tree Preorder Traversal",
"Binary Tree Postorder Traversal",
"Binary Tree Inorder Traversal",
"Maximum Depth of Binary Tree",
"Convert Binary Search Tree to Doubly Linked List"
]
},
"Linked List" : {
"nickname": "",
"property" : [
"Singly linked list",
"slow/fast快慢指针"
],
"problems" : [
"Reverse LinkedList",
"Nth to last Node in List",
"Convert Sorted List to Binary Search Tree",
"Copy List with Random Pointer",
"Linked List Cycle"
]
},
"Binary Search" : {
"nickname": "",
"property" : [
"start + 1 < end",
"mid = start + (end - start)",
"不同的题目，match的condition可能会不太一样"
],
"problems" : [
"Search for a Range",
"Search Insert Position",
"Search in Rotated Sorted Array",
"Search a 2D Matrix",
"First Bad Version",
"Find Peak Element",
""
]
},
"Rotate" : {
"nickname": "翻转",
"property" : [
"中间截开一段，放在前面",
"常常需要分段翻转几回，做一个reverse function"
],
"problems" : [
"Reverse Words in a string",
"Rotated String",
"Recover Sorted Array"
]
},
"Trie" : {
"nickname": "Just a Tree",
"property" : [
"HashMap, store word, search word"
],
"problems" : [
"Implement Trie",
"Add and Search Word",
"Word Search II",
]
},
"Segment Tree" : {
"nickname": "线段树",
"property" : [
"Split by (start + end)/2. Make left,right child, then bind back to root",
"which of these intervals contain a given point",
"which of these points are in a given interval"
],
"problems" : [
"Segment Tree Query",
"Segment Tree Modify",
"Segment Tree Build",
"Interval Sum",
"Interval Minimum Number",
"Count of Smaller Number",
"Count of Smaller Number before itself",
]
},
"Expression Tree" : {
"nickname": "",
"property" : [
"Need to remember how to build the tree just like Max-tree using stack. 'while' add stack.pop() to node.left; if stack !empty, stack.peek().right = node; add node into stack",
],
"problems" : [
"Expression Evaludation",
]
},
"Toposort" : {
"nickname": "Topological Sort",
"property" : [
"NO CYCLE: Only possible if the graph has no directed cycle.",
"Must have a Sink vertex, the most outgoing vertex, where it all ends",
