Data commit

Task/Mian-Chowla-sequence/C/mian-chowla-sequence-1.c

@@ -0,0 +1,45 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <time.h>
+
+#define n 100
+#define nn ((n * (n + 1)) >> 1)
+
+bool Contains(int lst[], int item, int size) {
+	for (int i = size - 1; i >= 0; i--)
+ 		if (item == lst[i]) return true;
+	return false;
+}
+
+int * MianChowla()
+{
+	static int mc[n]; mc[0] = 1;
+	int sums[nn];	sums[0] = 2;
+	int sum, le, ss = 1;
+	for (int i = 1; i < n; i++) {
+		le = ss;
+		for (int j = mc[i - 1] + 1; ; j++) {
+			mc[i] = j;
+			for (int k = 0; k <= i; k++) {
+				sum = mc[k] + j;
+				if (Contains(sums, sum, ss)) {
+					ss = le; goto nxtJ;
+				}
+				sums[ss++] = sum;
+			}
+			break;
+		nxtJ:;
+		}
+	}
+	return mc;
+}
+
+int main() {
+	clock_t st = clock(); int * mc; mc = MianChowla();
+        double et = ((double)(clock() - st)) / CLOCKS_PER_SEC;
+	printf("The first 30 terms of the Mian-Chowla sequence are:\n");
+	for (int i = 0; i < 30; i++) printf("%d ", mc[i]);
+	printf("\n\nTerms 91 to 100 of the Mian-Chowla sequence are:\n");
+	for (int i = 90; i < 100; i++) printf("%d ", mc[i]);
+	printf("\n\nComputation time was %f seconds.", et);
+}

Task/Mian-Chowla-sequence/C/mian-chowla-sequence-2.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <time.h>
+
+// helper function for indicating memory used.
+void approx(char* buf, double count)
+{
+    const char* suffixes[] = { "Bytes", "KiB", "MiB" };
+    uint s = 0;
+    while (count >= 1024 && s < 3) { s++; count /= 1024; }
+    if (count - (double)((int)count) == 0.0)
+        sprintf(buf, "%d %s", (int)count, suffixes[s]);
+    else
+        sprintf(buf, "%.1f %s", count, suffixes[s]);
+}
+
+int main() {
+    int i, j, k, c = 0, n = 100, nn = 110;
+    int* mc = (int*) malloc((n) * sizeof(int));
+    bool* isSum = (bool*) calloc(nn, sizeof(bool));
+    char em[] = "unable to increase isSum array to %ld.";
+    if (n > 100)  printf("Computing terms 1 to %d...\n", n);
+    clock_t st = clock();
+    for (i = 1; c < n; i++) {
+        mc[c] = i;
+        if (i + i > nn) {
+            bool* newIs = (bool*)realloc(isSum, (nn <<= 1) * sizeof(bool));
+            if (newIs == NULL) { printf(em, nn); return -1; }
+            isSum = newIs;
+            for (j = (nn >> 1); j < nn; j++) isSum[j] = false;
+        }
+        bool isUnique = true;
+        for (j = 0; (j < c) && isUnique; j++) isUnique = !isSum[i + mc[j]];
+        if (isUnique) {
+            for (k = 1; k <= c; k++) isSum[i + mc[k]] = true;
+            c++;
+        }
+    }
+    double et = 1e3 * ((double)(clock() - st)) / CLOCKS_PER_SEC;
+    free(isSum);
+    printf("The first 30 terms of the Mian-Chowla sequence are:\n");
+    for (i = 0; i < 30; i++) printf("%d ", mc[i]);
+    printf("\n\nTerms 91 to 100 of the Mian-Chowla sequence are:\n");
+    for (i = 90; i < 100; i++) printf("%d ", mc[i]);
+    if (c > 100) printf("\nTerm %d is: %d" ,c , mc[c - 1]);
+    free(mc);
+    char buf[100]; approx(buf, nn * sizeof(bool));
+    printf("\n\nComputation time was %6.3f ms.  Allocation was %s.", et, buf);
+}