(int root)
| 128 | // dfs2方法的递归版改迭代版 |
| 129 | // 不会改，看讲解118，讲了怎么从递归版改成迭代版 |
| 130 | public static void dfs2(int root) { |
| 131 | stackSize = 0; |
| 132 | push(root, 0, -1); |
| 133 | while (stackSize > 0) { |
| 134 | pop(); |
| 135 | if (e == -1) { |
| 136 | e = head[u]; |
| 137 | } else { |
| 138 | e = next[e]; |
| 139 | } |
| 140 | if (e != 0) { |
| 141 | push(u, f, e); |
| 142 | if (to[e] != f) { |
| 143 | push(to[e], u, -1); |
| 144 | } |
| 145 | } else { |
| 146 | for (int e = head[u], v; e != 0; e = next[e]) { |
| 147 | v = to[e]; |
| 148 | if (v != f) { |
| 149 | num[u] += num[v]; |
| 150 | } |
| 151 | } |
| 152 | } |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | public static void main(String[] args) throws IOException { |
| 157 | BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); |