Data commit

Task/Five-weekends/C/five-weekends-1.c

@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <time.h>
+
+static const char *months[] = {"January", "February", "March", "April", "May",
+    "June", "July", "August", "September", "October", "November", "December"};
+static int long_months[] = {0, 2, 4, 6, 7, 9, 11};
+
+int main() {
+    int n = 0, y, i, m;
+    struct tm t = {0};
+    printf("Months with five weekends:\n");
+    for (y = 1900; y <= 2100; y++) {
+        for (i = 0; i < 7; i++) {
+            m = long_months[i];
+            t.tm_year = y-1900;
+	    t.tm_mon = m;
+	    t.tm_mday = 1;
+            if (mktime(&t) == -1) { /* date not supported */
+                printf("Error: %d %s\n", y, months[m]);
+                continue;
+            }
+            if (t.tm_wday == 5) { /* Friday */
+                printf("  %d %s\n", y, months[m]);
+                n++;
+            }
+        }
+    }
+    printf("%d total\n", n);
+    return 0;
+}

Task/Five-weekends/C/five-weekends-2.c

@@ -0,0 +1,40 @@
+#include <stdio.h>
+#include <string.h>
+
+int check_month(int y, int m)
+{
+	char buf[1024], *ptr;
+	int bytes, *a = &m;
+
+	sprintf(buf, "ncal -m %d -M %d", m, y);
+	FILE *fp = popen(buf, "r");
+	if (!fp) return -1;
+
+	bytes = fread(buf, 1, 1024, fp);
+	fclose(fp);
+	buf[bytes] = 0;
+
+#define check_day(x) \
+	ptr = strstr(buf, x);\
+	if (5 != sscanf(ptr, x" %d %d %d %d %d", a, a, a, a, a)) return 0
+
+	check_day("Fr");
+	check_day("Sa");
+	check_day("Su");
+	return 1;
+}
+
+int main()
+{
+	int y, m, cnt = 0;
+	for (y = 1900; y <= 2100; y++) {
+		for (m = 1; m <= 12; m++) {
+			if (check_month(y, m) <= 0) continue;
+			printf("%d-%02d ", y, m);
+			if (++cnt % 16 == 0) printf("\n");
+		}
+	}
+	printf("\nTotal: %d\n", cnt);
+
+	return 0;
+}