Data commit

Task/Averages-Mode/C/averages-mode.c

@@ -0,0 +1,59 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct { double v; int c; } vcount;
+
+int cmp_dbl(const void *a, const void *b)
+{
+	double x = *(const double*)a - *(const double*)b;
+	return x < 0 ? -1 : x > 0;
+}
+
+int vc_cmp(const void *a, const void *b)
+{
+	return ((const vcount*)b)->c - ((const vcount*)a)->c;
+}
+
+int get_mode(double* x, int len, vcount **list)
+{
+	int i, j;
+	vcount *vc;
+
+	/* sort values */
+	qsort(x, len, sizeof(double), cmp_dbl);
+
+	/* count occurence of each value */
+	for (i = 0, j = 1; i < len - 1; i++, j += (x[i] != x[i + 1]));
+
+	*list = vc = malloc(sizeof(vcount) * j);
+	vc[0].v = x[0];
+	vc[0].c = 1;
+
+	/* generate list value-count pairs */
+	for (i = j = 0; i < len - 1; i++, vc[j].c++)
+		if (x[i] != x[i + 1]) vc[++j].v = x[i + 1];
+
+	/* sort that by count in descending order */
+	qsort(vc, j + 1, sizeof(vcount), vc_cmp);
+
+	/* the number of entries with same count as the highest */
+	for (i = 0; i <= j && vc[i].c == vc[0].c; i++);
+
+	return i;
+}
+
+int main()
+{
+	double values[] = { 1, 3, 6, 6, 6, 6, 7, 7, 12, 12, 12, 12, 17 };
+#	define len sizeof(values)/sizeof(double)
+	vcount *vc;
+
+	int i, n_modes = get_mode(values, len, &vc);
+
+	printf("got %d modes:\n", n_modes);
+	for (i = 0; i < n_modes; i++)
+		printf("\tvalue = %g, count = %d\n", vc[i].v, vc[i].c);
+
+	free(vc);
+	return 0;
+}