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67 | 67 |
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68 | 68 | <!-- 这里可写通用的实现逻辑 -->
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69 | 69 |
|
| 70 | +> 中文题意不容易读懂,可以参考[英文版本的题目描述](/solution/0600-0699/0655.Print%20Binary%20Tree/README_EN.md)。 |
| 71 | +
|
| 72 | +先求二叉树的高度 h,然后根据 h 求得结果列表的行数和列数 m, n。 |
| 73 | + |
| 74 | +根据 m, n 初始化结果列表,然后 dfs 遍历二叉树,依次在每个位置填入二叉树节点值(字符串形式)即可。 |
| 75 | + |
70 | 76 | <!-- tabs:start -->
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71 | 77 |
|
72 | 78 | ### **Python3**
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73 | 79 |
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74 | 80 | <!-- 这里可写当前语言的特殊实现逻辑 -->
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75 | 81 |
|
76 | 82 | ```python
|
| 83 | +# Definition for a binary tree node. |
| 84 | +# class TreeNode: |
| 85 | +# def __init__(self, val=0, left=None, right=None): |
| 86 | +# self.val = val |
| 87 | +# self.left = left |
| 88 | +# self.right = right |
| 89 | +class Solution: |
| 90 | + def printTree(self, root: TreeNode) -> List[List[str]]: |
| 91 | + def height(root): |
| 92 | + if root is None: |
| 93 | + return -1 |
| 94 | + return 1 + max(height(root.left), height(root.right)) |
| 95 | + |
| 96 | + def dfs(root, r, c): |
| 97 | + if root is None: |
| 98 | + return |
| 99 | + ans[r][c] = str(root.val) |
| 100 | + dfs(root.left, r + 1, c - 2 ** (h - r - 1)) |
| 101 | + dfs(root.right, r + 1, c + 2 ** (h - r - 1)) |
77 | 102 |
|
| 103 | + h = height(root) |
| 104 | + m, n = h + 1, 2 ** (h + 1) - 1 |
| 105 | + ans = [[""] * n for _ in range(m)] |
| 106 | + dfs(root, 0, (n - 1) // 2) |
| 107 | + return ans |
78 | 108 | ```
|
79 | 109 |
|
80 | 110 | ### **Java**
|
81 | 111 |
|
82 | 112 | <!-- 这里可写当前语言的特殊实现逻辑 -->
|
83 | 113 |
|
84 | 114 | ```java
|
| 115 | +/** |
| 116 | + * Definition for a binary tree node. |
| 117 | + * public class TreeNode { |
| 118 | + * int val; |
| 119 | + * TreeNode left; |
| 120 | + * TreeNode right; |
| 121 | + * TreeNode() {} |
| 122 | + * TreeNode(int val) { this.val = val; } |
| 123 | + * TreeNode(int val, TreeNode left, TreeNode right) { |
| 124 | + * this.val = val; |
| 125 | + * this.left = left; |
| 126 | + * this.right = right; |
| 127 | + * } |
| 128 | + * } |
| 129 | + */ |
| 130 | +class Solution { |
| 131 | + public List<List<String>> printTree(TreeNode root) { |
| 132 | + int h = height(root); |
| 133 | + int m = h + 1, n = (1 << (h + 1)) - 1; |
| 134 | + String[][] res = new String[m][n]; |
| 135 | + for (int i = 0; i < m; ++i) { |
| 136 | + Arrays.fill(res[i], ""); |
| 137 | + } |
| 138 | + dfs(root, res, h, 0, (n - 1) / 2); |
| 139 | + List<List<String>> ans = new ArrayList<>(); |
| 140 | + for (String[] t : res) { |
| 141 | + ans.add(Arrays.asList(t)); |
| 142 | + } |
| 143 | + return ans; |
| 144 | + } |
| 145 | + |
| 146 | + private void dfs(TreeNode root, String[][] res, int h, int r, int c) { |
| 147 | + if (root == null) { |
| 148 | + return; |
| 149 | + } |
| 150 | + res[r][c] = String.valueOf(root.val); |
| 151 | + dfs(root.left, res, h, r + 1, c - (1 << (h - r - 1))); |
| 152 | + dfs(root.right, res, h, r + 1, c + (1 << (h - r - 1))); |
| 153 | + } |
| 154 | + |
| 155 | + private int height(TreeNode root) { |
| 156 | + if (root == null) { |
| 157 | + return -1; |
| 158 | + } |
| 159 | + return 1 + Math.max(height(root.left), height(root.right)); |
| 160 | + } |
| 161 | +} |
| 162 | +``` |
| 163 | + |
| 164 | +### **C++** |
| 165 | + |
| 166 | +```cpp |
| 167 | +/** |
| 168 | + * Definition for a binary tree node. |
| 169 | + * struct TreeNode { |
| 170 | + * int val; |
| 171 | + * TreeNode *left; |
| 172 | + * TreeNode *right; |
| 173 | + * TreeNode() : val(0), left(nullptr), right(nullptr) {} |
| 174 | + * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} |
| 175 | + * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} |
| 176 | + * }; |
| 177 | + */ |
| 178 | +class Solution { |
| 179 | +public: |
| 180 | + vector<vector<string>> printTree(TreeNode* root) { |
| 181 | + int h = height(root); |
| 182 | + int m = h + 1, n = (1 << (h + 1)) - 1; |
| 183 | + vector<vector<string>> ans(m, vector<string>(n, "")); |
| 184 | + dfs(root, ans, h, 0, (n - 1) / 2); |
| 185 | + return ans; |
| 186 | + } |
| 187 | + |
| 188 | + void dfs(TreeNode* root, vector<vector<string>>& ans, int h, int r, int c) { |
| 189 | + if (!root) return; |
| 190 | + ans[r][c] = to_string(root->val); |
| 191 | + dfs(root->left, ans, h, r + 1, c - pow(2, h - r - 1)); |
| 192 | + dfs(root->right, ans, h, r + 1, c + pow(2, h - r - 1)); |
| 193 | + } |
| 194 | + |
| 195 | + int height(TreeNode* root) { |
| 196 | + if (!root) return -1; |
| 197 | + return 1 + max(height(root->left), height(root->right)); |
| 198 | + } |
| 199 | +}; |
| 200 | +``` |
| 201 | +
|
| 202 | +### **Go** |
| 203 | +
|
| 204 | +```go |
| 205 | +/** |
| 206 | + * Definition for a binary tree node. |
| 207 | + * type TreeNode struct { |
| 208 | + * Val int |
| 209 | + * Left *TreeNode |
| 210 | + * Right *TreeNode |
| 211 | + * } |
| 212 | + */ |
| 213 | +func printTree(root *TreeNode) [][]string { |
| 214 | + var height func(root *TreeNode) int |
| 215 | + height = func(root *TreeNode) int { |
| 216 | + if root == nil { |
| 217 | + return -1 |
| 218 | + } |
| 219 | + return 1 + max(height(root.Left), height(root.Right)) |
| 220 | + } |
| 221 | + h := height(root) |
| 222 | + m, n := h+1, (1<<(h+1))-1 |
| 223 | + ans := make([][]string, m) |
| 224 | + for i := range ans { |
| 225 | + ans[i] = make([]string, n) |
| 226 | + for j := range ans[i] { |
| 227 | + ans[i][j] = "" |
| 228 | + } |
| 229 | + } |
| 230 | + var dfs func(root *TreeNode, r, c int) |
| 231 | + dfs = func(root *TreeNode, r, c int) { |
| 232 | + if root == nil { |
| 233 | + return |
| 234 | + } |
| 235 | + ans[r][c] = strconv.Itoa(root.Val) |
| 236 | + dfs(root.Left, r+1, c-int(math.Pow(float64(2), float64(h-r-1)))) |
| 237 | + dfs(root.Right, r+1, c+int(math.Pow(float64(2), float64(h-r-1)))) |
| 238 | + } |
| 239 | +
|
| 240 | + dfs(root, 0, (n-1)/2) |
| 241 | + return ans |
| 242 | +} |
85 | 243 |
|
| 244 | +func max(a, b int) int { |
| 245 | + if a > b { |
| 246 | + return a |
| 247 | + } |
| 248 | + return b |
| 249 | +} |
86 | 250 | ```
|
87 | 251 |
|
88 | 252 | ### **...**
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