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Commit 1368357

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"Find Median from Data Stream": alt to c solution
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3 files changed

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‎README.md

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@@ -26,7 +26,7 @@ The `☢` means that you need to have a LeetCode Premium Subscription.
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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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| 295 | [Find Median from Data Stream] | [C](src/295.c) |
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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) |

‎src/295.c

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#include <stdio.h>
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#include <stdlib.h>
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static const int MAXN = 102400;
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struct MedianFinder {
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int *maxHeap; /* store the smaller half */
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int *minHeap; /* store the larger half */
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int maxHeapSize;
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int minHeapSize;
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double medium;
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};
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void swap(int *a, int *b) {
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int c = *a;
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*a = *b;
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*b = c;
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}
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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(int *heap, int size) {
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int parent, child;
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child = size - 1;
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while (child > 0) {
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parent = (child - 1) / 2;
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if (heap[parent] < heap[child])
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swap(&heap[parent], &heap[child]);
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child = parent;
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}
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}
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void siftDownMax(int *heap, int size) {
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int parent, child;
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parent = 0; child = 1;
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while (child < size) {
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if (child + 1 < size && heap[child] < heap[child + 1])
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child = child + 1;
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if (heap[parent] >= heap[child]) break;
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swap(&heap[parent], &heap[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(int *heap, int size) {
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int parent, child;
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child = size - 1;
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while (child > 0) {
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parent = (child - 1) / 2;
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if (heap[parent] > heap[child])
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swap(&heap[parent], &heap[child]);
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child = parent;
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}
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}
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void siftDownMin(int *heap, int size) {
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int parent, child;
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parent = 0; child = 1;
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while (child < size) {
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if (child + 1 < size && heap[child] > heap[child + 1])
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child = child + 1;
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if (heap[parent] <= heap[child]) break;
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swap(&heap[parent], &heap[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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/** Initialize your data structure here. */
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struct MedianFinder* MedianFinderCreate() {
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struct MedianFinder *mf = (struct MedianFinder *)malloc(sizeof(struct MedianFinder));
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mf->maxHeap = (int *)malloc(MAXN * sizeof(int));
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mf->minHeap = (int *)malloc(MAXN * sizeof(int));
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mf->minHeapSize = mf->maxHeapSize = 0;
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mf->medium = 0;
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return mf;
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}
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/** Inserts a num into the data structure. */
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void addNum(struct MedianFinder* mf, int num) {
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if (mf == NULL) return;
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if (mf->maxHeapSize == mf->minHeapSize) {
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if (num > mf->medium) {
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addheap(mf->minHeap, &mf->minHeapSize, num);
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siftUpMin(mf->minHeap, mf->minHeapSize);
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mf->medium = mf->minHeap[0];
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}
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else {
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addheap(mf->maxHeap, &mf->maxHeapSize, num);
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siftUpMax(mf->maxHeap, mf->maxHeapSize);
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mf->medium = mf->maxHeap[0];
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}
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}
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else {
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if (num > mf->minHeap[0]) {
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addheap(mf->minHeap, &mf->minHeapSize, num);
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siftUpMin(mf->minHeap, mf->minHeapSize);
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if (mf->minHeapSize >= mf->maxHeapSize + 2) {
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addheap(mf->maxHeap, &mf->maxHeapSize, mf->minHeap[0]);
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siftUpMax(mf->maxHeap, mf->maxHeapSize);
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swap(&mf->minHeap[0], &mf->minHeap[mf->minHeapSize - 1]);
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mf->minHeapSize--;
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siftDownMin(mf->minHeap, mf->minHeapSize);
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}
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}
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else {
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addheap(mf->maxHeap, &mf->maxHeapSize, num);
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siftUpMax(mf->maxHeap, mf->maxHeapSize);
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if (mf->maxHeapSize >= mf->minHeapSize + 2) {
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addheap(mf->minHeap, &mf->minHeapSize, mf->maxHeap[0]);
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siftUpMin(mf->minHeap, mf->minHeapSize);
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swap(&mf->maxHeap[0], &mf->maxHeap[mf->maxHeapSize - 1]);
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mf->maxHeapSize--;
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siftDownMax(mf->maxHeap, mf->maxHeapSize);
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}
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}
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mf->medium = mf->maxHeap[0] + (mf->minHeap[0] - mf->maxHeap[0]) / 2.0;
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}
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}
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/** find the median of current data stream */
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double findMedian(struct MedianFinder* mf) {
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if (mf == NULL) return 0;
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return mf->medium;
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}
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/** Deallocates memory previously allocated for the data structure. */
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void MedianFinderFree(struct MedianFinder* mf) {
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if (mf == NULL) return;
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free(mf->maxHeap);
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free(mf->minHeap);
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free(mf);
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}
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// Your MedianFinder object will be instantiated and called as such:
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// struct MedianFinder* mf = MedianFinderCreate();
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// addNum(mf, 1.0);
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// findMedian(mf);
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// MedianFinderFree(mf);
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int main() {
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struct MedianFinder* mf = MedianFinderCreate();
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addNum(mf, 1);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 2);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 3);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 4);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 5);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 6);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 7);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 8);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 9);
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printf("%lf\n", findMedian(mf));
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addNum(mf, 10);
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printf("%lf\n", findMedian(mf));
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MedianFinderFree(mf);
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return 0;
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}

‎src/295.cpp

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