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maxHeap
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‎Java/HashHeap.java‎

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tags: HashHeap
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非题.是从九章找来的HashHeap implementation.
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Java/Building Outline.java renamed to Java/The Skyline Problem.java

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又叫做skyline. 用Sweep Line做的O(nLogN), 但是貌似还有很多做法: segement tree, hashheap, treeSet?
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#### 方法1: Sweep Line, Time O(nLogN), Space O(n)
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original reference http://codechen.blogspot.com/2015/06/leetcode-skyline-problem.html?_sm_au_=isVmHvFmFs40TWRt
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sweep line:
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#### Sweep Line, Time O(nLogN), Space O(n)
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- original reference http://codechen.blogspot.com/2015/06/leetcode-skyline-problem.html?_sm_au_=isVmHvFmFs40TWRt
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- 画图分析: 需要找到 non-overlaping height point at current index; also height needs to be different than prev height peek to be visible.
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- 把所有点分出来， 每个点有index x, 再加上一个height.
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- 在这个list上排序，根据index和height. 注意用负数标记building start point height, 这样保证start在end 之前
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- 用负数的height标记start: 在priority queue里面同一个x-pos比较 startPoint.height, endPoint.height 的时候, 因为end height是整数, 所以compare时会自动把start point放在end point前面
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- 当然了, 如果两个 start point比较, 第二个point的负数超大的话(也就是height很高), 就会顺理compare return正数, 成章形成倒位
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- 在processs时候用max-heap (reversed priorityqueue)，再iterate heightPoints 来存最大的height . 遇到peek,就是一个合理的解
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- heightQueue里面加一个0, 用来在结尾的时候做closure
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#### 方法2: Segment Tree
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REVIEW
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#### Segment Tree
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- 看了一些做法, segment tree写法很复杂, 估计在面试中难以用segment tree来写: https://www.cnblogs.com/tiezhibieek/p/5021202.html
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#### HashHeap
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- HashHeap template 可以考虑: https://www.jiuzhang.com/solution/building-outline/#tag-highlight-lang-java
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Binary Indexed Tree?
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HashHeap?
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```
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/*
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queue.offer(new Point(buildings[i][1], buildings[i][2]));
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}
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// Mark height and calcualte the outline point.
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// Mark and store height in maxHeap: start and end with ground point height=0
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PriorityQueue<Integer> maxHeightQueue = new PriorityQueue<>(Collections.reverseOrder());
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maxHeightQueue.offer(0);
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int prevPeak = maxHeightQueue.peek();
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// Find non-overlaping height. Positive height marks end of building outline, so remove from maxHeap.
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while (!queue.isEmpty()) {
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Point point = queue.poll();
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if (point.height < 0) {
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maxHeightQueue.remove(point.height);
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}
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// Goal: find non-overlapping height
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int currPeak = maxHeightQueue.peek();
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if (currPeak != prevPeak) {
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rst.add(new int[]{point.pos, currPeak});

‎LevelReviewPage.md‎

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‎README.md‎

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‎ReviewPage.md‎

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‎TagREADME.md‎

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* [Matrix DFS (2)](#matrix-dfs-2)
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* [Queue (2)](#queue-2)
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* [Geometry (2)](#geometry-2)
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* [HashHeap (1)](#hashheap-1)
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* [KMP (1)](#kmp-1)
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* [Brainteaser (1)](#brainteaser-1)
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* [Interval (1)](#interval-1)
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|9|[Unique Binary Search Tree II.java](https://github.com/awangdev/LintCode/blob/master/Java/Unique%20Binary%20Search%20Tree%20II.java)|Medium|Java|[BST, DP, Divide and Conquer, Tree]||
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|10|[Count of Range Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20of%20Range%20Sum.java)|Hard|Java|[BST, Divide and Conquer, Merge Sort, PreSum]||
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|11|[Expression Add Operators.java](https://github.com/awangdev/LintCode/blob/master/Java/Expression%20Add%20Operators.java)|Hard|Java|[Backtracking, DFS, Divide and Conquer, String]||
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|12|[Building Outline.java](https://github.com/awangdev/LintCode/blob/master/Java/Building%20Outline.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|12|[The Skyline Problem.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Skyline%20Problem.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|13|[Find Peak Element II.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20Peak%20Element%20II.java)|Hard|Java|[Binary Search, DFS, Divide and Conquer]||
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|14|[Search a 2D Matrix II.java](https://github.com/awangdev/LintCode/blob/master/Java/Search%20a%202D%20Matrix%20II.java)|Medium|Java|[Binary Search, Divide and Conquer]||
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|15|[Interval Minimum Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Interval%20Minimum%20Number.java)|Medium|Java|[Binary Search, Divide and Conquer, Lint, Segment Tree]||
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| Squence | Problem | Level | Language | Tags | Video Tutorial|
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|:-------:|:--------------|:------:|:---------:|:----:|:-------------:|
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|0|[Trapping Rain Water II.java](https://github.com/awangdev/LintCode/blob/master/Java/Trapping%20Rain%20Water%20II.java)|Hard|Java|[BFS, Heap]||
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|1|[Building Outline.java](https://github.com/awangdev/LintCode/blob/master/Java/Building%20Outline.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|1|[The Skyline Problem.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Skyline%20Problem.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|2|[Kth Smallest Number in Sorted Matrix.java](https://github.com/awangdev/LintCode/blob/master/Java/Kth%20Smallest%20Number%20in%20Sorted%20Matrix.java)|Medium|Java|[Binary Search, Heap]||
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|3|[Ugly Number II.java](https://github.com/awangdev/LintCode/blob/master/Java/Ugly%20Number%20II.java)|Medium|Java|[DP, Heap, Math]||
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|4|[Data Stream Median.java](https://github.com/awangdev/LintCode/blob/master/Java/Data%20Stream%20Median.java)|Hard|Java|[Design, Heap]||
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| Squence | Problem | Level | Language | Tags | Video Tutorial|
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|:-------:|:--------------|:------:|:---------:|:----:|:-------------:|
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|0|[Count of Smaller Numbers After Self.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20of%20Smaller%20Numbers%20After%20Self.java)|Hard|Java|[BST, Binary Indexed Tree, Binary Search, Divide and Conquer, Segment Tree]||
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|1|[Building Outline.java](https://github.com/awangdev/LintCode/blob/master/Java/Building%20Outline.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|1|[The Skyline Problem.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Skyline%20Problem.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|2|[Interval Minimum Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Interval%20Minimum%20Number.java)|Medium|Java|[Binary Search, Divide and Conquer, Lint, Segment Tree]||
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|3|[Interval Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Interval%20Sum.java)|Medium|Java|[Binary Search, Lint, Segment Tree]||
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|4|[Interval Sum II.java](https://github.com/awangdev/LintCode/blob/master/Java/Interval%20Sum%20II.java)|Hard|Java|[Binary Search, Lint, Segment Tree]||
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|:-------:|:--------------|:------:|:---------:|:----:|:-------------:|
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|0|[Number of Airplane in the sky.java](https://github.com/awangdev/LintCode/blob/master/Java/Number%20of%20Airplane%20in%20the%20sky.java)|Medium|Java|[Array, Interval, PriorityQueue, Sort, Sweep Line]||
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|1|[Merge Intervals.java](https://github.com/awangdev/LintCode/blob/master/Java/Merge%20Intervals.java)|Medium|Java|[Array, PriorityQueue, Sort, Sweep Line]||
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|2|[Building Outline.java](https://github.com/awangdev/LintCode/blob/master/Java/Building%20Outline.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|2|[The Skyline Problem.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Skyline%20Problem.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|3|[Meeting Rooms II.java](https://github.com/awangdev/LintCode/blob/master/Java/Meeting%20Rooms%20II.java)|Medium|Java|[Greedy, Heap, Sort, Sweep Line]||
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|4|[Meeting Rooms.java](https://github.com/awangdev/LintCode/blob/master/Java/Meeting%20Rooms.java)|Easy|Java|[PriorityQueue, Sort, Sweep Line]||
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| Squence | Problem | Level | Language | Tags | Video Tutorial|
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|:-------:|:--------------|:------:|:---------:|:----:|:-------------:|
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|0|[Count of Smaller Numbers After Self.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20of%20Smaller%20Numbers%20After%20Self.java)|Hard|Java|[BST, Binary Indexed Tree, Binary Search, Divide and Conquer, Segment Tree]||
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|1|[Building Outline.java](https://github.com/awangdev/LintCode/blob/master/Java/Building%20Outline.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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|1|[The Skyline Problem.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Skyline%20Problem.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, Segment Tree, Sweep Line]||
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## HashHeap (1)
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| Squence | Problem | Level | Language | Tags | Video Tutorial|
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|:-------:|:--------------|:------:|:---------:|:----:|:-------------:|
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|0|[HashHeap.java](https://github.com/awangdev/LintCode/blob/master/Java/HashHeap.java)|Hard|Java|[HashHeap]||
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## KMP (1)
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| Squence | Problem | Level | Language | Tags | Video Tutorial|
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|:-------:|:--------------|:------:|:---------:|:----:|:-------------:|

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