Merge pull request #102 from RichardWeiYang/master

counting sort in c

Author: wangzheng0822

c-cpp/12_sorts/merge_sort.c

@@ -0,0 +1,84 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+void dump(int *arr, int size)
+{
+	int idx;
+
+	for (idx = 0; idx < size; idx++)
+		printf("%08d\n", arr[idx]);
+}
+
+void __merge(int *arr, int p, int q, int r)
+{
+	int *tmp;
+	int i, j, k;
+
+	tmp = (int*)malloc((r - p + 1) * sizeof(int));
+
+	if (!tmp)
+		abort();
+
+	for (i = p, j = q + 1, k = 0; i <= q && j <= r;) {
+		if (arr[i] <= arr[j])
+			tmp[k++] = arr[i++];
+		else
+			tmp[k++] = arr[j++];
+	}
+
+	if (i == q + 1) {
+		for (; j <= r;)
+			tmp[k++] = arr[j++];
+	} else {
+		for (; i <= q;)
+			tmp[k++] = arr[i++];
+	}
+
+	memcpy(arr + p, tmp, (r - p + 1) * sizeof(int));
+	free(tmp);
+}
+
+void __merge_sort(int *arr, int p, int r)
+{
+	int q;
+
+	if (p >= r)
+		return;
+
+	q = (p + r) / 2;
+	__merge_sort(arr, p, q);
+	__merge_sort(arr, q + 1, r);
+	__merge(arr, p, q, r);
+}
+
+void merge_sort(int *arr, int size)
+{
+	__merge_sort(arr, 0, size - 1);
+}
+
+void merge_verify()
+{
+	int test[10] = {5, 8, 9, 23, 67, 1, 3, 7, 31, 56};
+
+	__merge(test, 0, 4, 9);
+
+	dump(test, 10);
+}
+
+void merge_sort_test()
+{
+	int test[10] = {5, 8, 9, 23, 67, 1, 3, 7, 31, 56};
+
+	merge_sort(test, 10);
+
+	dump(test, 10);
+}
+
+int main()
+{
+	//merge_verify();
+	merge_sort_test();
+	return 0;
+}

c-cpp/12_sorts/quick_sort.c

@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+void dump(int *arr, int size)
+{
+	int idx;
+
+	for (idx = 0; idx < size; idx++)
+		printf("%08d\n", arr[idx]);
+}
+
+void swap(int *a, int *b)
+{
+	int tmp = *a;
+	*a = *b;
+	*b = tmp;
+}
+
+int partition(int *arr, int p, int r)
+{
+	//int pivot = arr[r];
+	int i, j;
+
+	i = j = p;
+
+	for (; j < r; j++) {
+		if (arr[j] < arr[r]) {
+			swap(arr + i, arr + j);
+			i++;
+		}
+	}
+	
+	swap(arr + i, arr + r);
+	return i;
+}
+
+void __quick_sort(int *arr, int p, int r)
+{
+	int q;
+
+	if (p >= r)
+		return;
+
+	q = partition(arr, p, r);
+	__quick_sort(arr, p, q-1);
+	__quick_sort(arr, q+1, r);
+}
+
+void quick_sort(int *arr, int size)
+{
+	__quick_sort(arr, 0, size - 1);
+}
+
+void quick_sort_test()
+{
+	int test[10] = {5, 8, 9, 23, 67, 1, 3, 7, 31, 56};
+
+	quick_sort(test, 10);
+
+	dump(test, 10);
+}
+
+int main()
+{
+	quick_sort_test();
+	return 0;
+}

c-cpp/14_sorts/counting_sort.c

@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+void dump(int *arr, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		printf("%08d\n", arr[i]);
+}
+
+// content in arr must be positive integer
+void counting_sort(int *arr, int size)
+{
+	int max, i;
+	int *count, *tmp;
+
+	if (size <= 1)
+		return;
+
+	max = 0;
+	// find the biggest integer
+	for (i = 0; i < size; i++) {
+		if (max < arr[i])
+			max = arr[i];
+	}
+
+	// init count to 0
+	count = (int*)malloc((max+1) * sizeof(int));
+	tmp = (int*)malloc(size * sizeof(int));
+	if (!count || !tmp)
+		return;
+	memset(count, 0, (max + 1) * sizeof(int));
+
+	// counting
+	for (i = 0; i < size; i++)
+		count[arr[i]]++;
+	for (i = 1; i < max + 1; i++)
+		count[i] = count[i-1] + count[i];
+
+	// iterate arr and put it to the correct index in tmp
+	for (i = 0; i < size; i++){
+		int index = count[arr[i]] - 1;
+		tmp[index] = arr[i];
+		count[arr[i]]--;
+	}
+
+	// move back to arr
+	memcpy(arr, tmp, size * sizeof(int));
+}
+
+void counting_sort_test()
+{
+	int test_data[10] = {3, 23, 98, 1, 27, 36, 52, 89, 76, 44};
+
+	counting_sort(test_data, 10);
+	dump(test_data, 10);
+}
+
+int main()
+{
+	counting_sort_test();
+	return 0;
+}