#include using namespace std; const int N = 1 << 12; const int M = 4 * N; int n, m, t; // 链式前向星 int e[M], h[N], idx, w[M], ne[M]; void add(int a, int b, int c = 0) { e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++; } vector stk; void dfs(int u) { while (~h[u]) { int y = e[h[u]]; h[u] = ne[h[u]]; dfs(y); } stk.push_back(u); } int main() { memset(h, -1, sizeof h); // 初始化链式前向星 scanf("%d", &n); // n个传感器 int t = (1 << (n - 1)) - 1; for (int i = 0; i < (1 << (n - 1)); i++) { add(i, ((i << 1) & t) | 1); add(i, (i << 1) & t); } dfs(0); printf("%d ", 1 << n); while (stk.size() > 1) putchar((stk.back() >> (n - 2)) + '0'), stk.pop_back(); puts(""); return 0; }