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

2025.02.28/03Ex/solve.c

@@ -0,0 +1,21 @@
+#include "solve.h"
+
+int t3_solve(char **a, int n, char *x, int (*cmp)(const char *, const char *)) {
+    int i = 0, j = n-1;
+    char *temp;
+
+    while (1) 
+    {
+        for (; i < n; i++) if (cmp(a[i], x) >= 0) break;
+        for (; j >= 0; j--) if (cmp(a[j], x) < 0) break;
+
+        if (i >= j) break;
+	temp = a[i];
+	a[i] = a[j];
+	a[j] = temp;
+
+	i++, j--;
+    }
+
+    return i;
+}