下面代码采用分治算法求解标准 3 柱汉诺塔问题，时间复杂度为 $O(n\log n)$。

1void move(vector<int> &src, vector<int> &tar) {2   int pan = src.back();3   src.pop_back();4   tar.push_back(pan);5}6 7void dfs(int n, vector<int> &src, vector<int> &buf, vector<int> &tar) {8   if (n == 1) {9      move(src, tar);10      return;11   }12 13   dfs(n - 1, src, tar, buf);14   move(src, tar);15   dfs(n - 1, buf, src, tar);16}17 18void solveHanota(vector<int> &A, vector<int> &B, vector<int> &C) {19   int n = A.size();20   dfs(n, A, B, C);21}