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Commit 99d38cc

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"Find Median from Data Stream"
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‎README.md

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| | Problem | Solution |
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| --- | ------------------------------------------------------------ | ------------------ |
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| 296 | [Best Meeting Point] ☢ | |
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| 295 | [Find Median from Data Stream] | [C++](src/295.cpp) |
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| 294 | [Flip Game II] ☢ | |
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| 293 | [Flip Game] ☢ | |
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| 292 | [Nim Game] | [C](src/292.c) |
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| 291 | [Word Pattern II] ☢ | |
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| 290 | [Word Pattern] | [C++](src/290.cpp) |
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[LeetCode algorithm problems]: https://leetcode.com/problemset/algorithms/
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[Best Meeting Point]: https://leetcode.com/problems/best-meeting-point/
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[Find Median from Data Stream]: https://leetcode.com/problems/find-median-from-data-stream/
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[Flip Game II]: https://leetcode.com/problems/flip-game-ii/
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[Flip Game]: https://leetcode.com/problems/flip-game/
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[Nim Game]: https://leetcode.com/problems/nim-game/
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[Word Pattern II]: https://leetcode.com/problems/word-pattern-ii/
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[Word Pattern]: https://leetcode.com/problems/word-pattern/

‎src/295.cpp

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#include <iostream>
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using namespace std;
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class MedianFinder {
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static const int MAXN = 102400;
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int maxHeap[MAXN]; // store the smaller half
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int minHeap[MAXN]; // store the bigger half
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int max_heap_size = 0;
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int min_heap_size = 0;
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double medium = 0;
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void addheap(int *heap, int &size, int data) {
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if (size < MAXN - 1) {
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heap[size] = data;
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size++;
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}
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}
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void siftUpMax() {
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int parent, child;
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child = max_heap_size - 1;
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while (child > 0) {
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parent = (child - 1) / 2;
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if (maxHeap[parent] < maxHeap[child])
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swap(maxHeap[parent], maxHeap[child]);
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child = parent;
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}
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}
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void siftDownMax() {
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int parent, child;
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parent = 0; child = 1;
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while (child < max_heap_size) {
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if (child + 1 < max_heap_size && maxHeap[child] < maxHeap[child + 1])
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child = child + 1;
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if (maxHeap[parent] >= maxHeap[child]) break;
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swap(maxHeap[parent], maxHeap[child]);
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parent = child;
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child = parent * 2 + 1;
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}
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}
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void siftUpMin() {
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int parent, child;
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child = min_heap_size - 1;
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while (child > 0) {
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parent = (child - 1) / 2;
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if (minHeap[parent] > minHeap[child])
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swap(minHeap[parent], minHeap[child]);
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child = parent;
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}
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}
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void siftDownMin() {
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int parent, child;
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parent = 0; child = 1;
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while (child < min_heap_size) {
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if (child + 1< min_heap_size && minHeap[child] > minHeap[child + 1])
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child = child + 1;
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if (minHeap[parent] <= minHeap[child]) break;
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swap(minHeap[parent], minHeap[child]);
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parent = child;
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child = parent * 2 + 1;
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}
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}
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public:
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// Adds a number into the data structure.
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void addNum(int num) {
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if (max_heap_size == min_heap_size) {
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if (num > medium) {
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addheap(minHeap, min_heap_size, num);
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siftUpMin();
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medium = minHeap[0];
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}
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else {
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addheap(maxHeap, max_heap_size, num);
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siftUpMax();
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medium = maxHeap[0];
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}
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}
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else {
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if (num > minHeap[0]) {
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addheap(minHeap, min_heap_size, num);
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siftUpMin();
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if (min_heap_size >= max_heap_size + 2) {
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addheap(maxHeap, max_heap_size, minHeap[0]);
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siftUpMax();
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swap(minHeap[0], minHeap[min_heap_size - 1]);
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min_heap_size--;
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siftDownMin();
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}
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}
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else {
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addheap(maxHeap, max_heap_size, num);
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siftUpMax();
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if (max_heap_size >= min_heap_size + 2) {
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addheap(minHeap, min_heap_size, maxHeap[0]);
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siftUpMin();
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swap(maxHeap[0], maxHeap[max_heap_size - 1]);
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max_heap_size--;
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siftDownMax();
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}
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}
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medium = maxHeap[0] + (minHeap[0] - maxHeap[0]) / 2.0;
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}
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}
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// Returns the median of current data stream
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double findMedian() {
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return medium;
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}
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};
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int main() {
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MedianFinder mf;
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mf.addNum(1);
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cout << mf.findMedian() << endl;
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mf.addNum(2);
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cout << mf.findMedian() << endl;
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mf.addNum(3);
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cout << mf.findMedian() << endl;
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mf.addNum(4);
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cout << mf.findMedian() << endl;
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mf.addNum(5);
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cout << mf.findMedian() << endl;
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mf.addNum(6);
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cout << mf.findMedian() << endl;
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mf.addNum(7);
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cout << mf.findMedian() << endl;
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mf.addNum(8);
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cout << mf.findMedian() << endl;
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mf.addNum(9);
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cout << mf.findMedian() << endl;
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mf.addNum(10);
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cout << mf.findMedian() << endl;
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return 0;
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}

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