Merge branch 'mowgli' week8

week8/quicksort.c

@@ -0,0 +1,161 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "quicksort.h"
+
+int main() {
+	/* size of test data */
+	int size_1 = 10;
+	int size_2 = 100000;
+
+	int *A1, *A2;
+	clock_t start, end;
+
+	printf("Allocating 10 test data space for A1...\n");
+	A1 = (int *)malloc(sizeof(int) * size_1);
+	if (A1 == NULL) {
+		printf("Fatal: can not allocate A1 space\n");
+		exit(1);
+	}
+
+	printf("Create random integer for A1...\n");
+	for (int i = 0; i < size_1; i++) {
+		A1[i] = rand();
+	}
+
+	printf("Testing quick sort...\n");
+	start = clock();
+	QuickSort(A1, 0, size_1 - 1);
+	end = clock();
+	_PrintClockInterval(start, end);
+
+	if (Check(A1, size_1)) {
+		printf("Checking result... pass\n");
+	} else {
+		printf("Checking result... fail\n");
+	}
+
+	printf("Freeing space of A1\n");
+	free(A1);
+	A1 = NULL;
+
+	printf("Allocating 100000 test data space for A2...\n");
+	A2 = (int *)malloc(sizeof(int) * size_2);
+	if (A2 == NULL) {
+		printf("Fatal: can not allocate A1 space\n");
+		exit(1);
+	}
+
+	printf("Create random integer for A2...\n");
+	for (int i = 0; i < size_2; i++) {
+		A2[i] = rand();
+	}
+
+	printf("Testing merge sort...\n");
+	start = clock();
+	QuickSort(A2, 0, size_2 - 1);
+	end = clock();
+	PrintClockInterval(start, end);
+
+	if (Check(A2, size_2)) {
+		printf("Checking result... pass\n");
+	} else {
+		printf("Checking result... fail\n");
+	}
+
+	printf("Freeing space of A2\n");
+	free(A2);
+	A2 = NULL;
+
+	return 0;
+}
+
+void QuickSort(int *A, int left, int right) {
+	int q;
+	if (left >= right) {
+		return;
+	}
+	/* q is the position of the pivot */
+	q = Partition(A, left, right);
+	QuickSort(A, left, q - 1);
+	QuickSort(A, q + 1, right);
+}
+
+int Partition(int *A, int left, int right) {
+	/* p is the position of the pivot */
+	int p;
+	p = Pivot(A, left, right);
+	/* use i, j, pivot to locate left, right, and pivot */
+	int i, j, pivot;
+	Swap(A, p, right);
+	i = left, j = right - 1, pivot = A[right];
+	while (true) {
+		while (i < right && A[i] < pivot)
+			i++;
+		while (j >= left && A[j] > pivot)
+			j--;
+		if (i < j)
+			Swap(A, i++, j--);
+		else
+			break;
+	}
+	Swap(A, i, right);
+	return i;
+}
+
+int Pivot(int *A, int left, int right) {
+	int middle = 0;
+	middle = (left + right) / 2;
+
+	if (A[left] > A[middle]) {
+		if (A[middle] > A[right]) {
+			middle = middle;
+		} else if (A[right] > A[left]) {
+			middle = left;
+		} else {
+			middle = right;
+		}
+	} else {
+		if (A[middle] < A[right]) {
+			middle = middle;
+		} else if (A[right] < A[left]) {
+			middle = left;
+		} else {
+			middle = right;
+		}
+	}
+	return middle;
+}
+
+void Swap(int *A, int x, int y) {
+	int tmp;
+	tmp = A[x];
+	A[x] = A[y];
+	A[y] = tmp;
+}
+
+bool Check(int *A, int size) {
+	if (size == 1) {
+		return true;
+	}
+
+	for (int i = 0; i < size - 1; i++) {
+		/* return false if find any disorder */
+		if (A[i] > A[i + 1]) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+void PrintClockInterval(clock_t start, clock_t end) {
+	printf("the time cost of this algorithms is %ld ms\n",
+			(end - start) / (CLOCKS_PER_SEC / 1000));
+}
+
+/* use this to check small size of data */
+void _PrintClockInterval(clock_t start, clock_t end) {
+	printf("the time cost of this algorithms is %ld ms\n", (end - start));
+}

week8/quicksort.h

@@ -0,0 +1,24 @@
+#include <stdbool.h>
+#include <time.h>
+
+/* Sort array A[left..right] using quick sort
+ * Pivot is picked using median-of-3 */
+void QuickSort(int *A, int left, int right);
+
+/* Sort the array in order */
+int Partition(int *A, int left, int right);
+
+/* pick the middle value between A[left], A[middle], A[right] */
+int Pivot(int *A, int left, int right);
+
+/* Swap A[x], A[y] */
+void Swap(int *A, int x, int y);
+
+/* create check functions */
+bool Check(int *A, int size);
+
+/* print the time of small data */
+void PrintClockInterval(clock_t start, clock_t end);
+
+/* use this to check small size of data */
+void _PrintClockInterval(clock_t start, clock_t end);