refactor(structure): normalize folder names with leading zeros for consistency

- Renamed all folders from format NEx (e.g., 1Ex, 2Ex...) to 0NEx (01Ex, 02Ex, etc.)
- Updated subdirectories and files accordingly
- Removed old main Makefile and tasks (a01.c–a09.c, solve.c, io_status.h), likely obsolete
- Cleaned up deprecated task binaries and configs

2025.02.21/07Ex/solve.c

@@ -0,0 +1,39 @@
+#include "solve.h"
+
+int t7_solve(char ** a, int n, char *s) {
+	bool fl_lst = false, fl_cur = false, fl_nxt = false;
+	int i, j;
+
+	if (strcmp(a[0], s) < 0) fl_cur = true;
+
+	for (i = 1, j = 0; i < n; ++i) {
+		if (strcmp(a[i], s) < 0) {
+			fl_lst = true;
+			fl_nxt = true;
+		}
+
+		if (!fl_lst) {
+			if (j != (i-1)) {
+				a[j] = a[i-1];
+			}
+			j++;
+		} else {
+			free(a[i-1]);
+		}
+		
+		fl_lst = fl_cur;
+		fl_cur = fl_nxt;
+		fl_nxt = false;
+	}
+
+	if (fl_lst)
+	{
+		free(a[i-1]);
+	} else {
+		a[j++] = a[i-1];
+	}
+
+	for (i = j; i < n; ++i) a[i] = 0;
+
+	return j;
+}