解题思路:
这道题的意思是,给定n,求出所有包含1-n值的中序遍历树
提交代码:
class Solution {
public List<TreeNode> generateTrees(int n) {
List<TreeNode> res=new ArrayList<TreeNode>();
if(n<1) return res;
return generateTrees(1, n);
}
private List<TreeNode> generateTrees(int left, int right) {
List<TreeNode> res = new ArrayList<TreeNode>();
if (left > right) {
res.add(null);
return res;
}
for (int i = left; i <= right; i++) {
List<TreeNode> leftRes = generateTrees(left, i - 1);
List<TreeNode> rightRes = generateTrees(i + 1, right);
for (int j = 0; j < leftRes.size(); j++) {
for (int k = 0; k < rightRes.size(); k++) {
TreeNode root = new TreeNode(i);
root.left = leftRes.get(j);
root.right = rightRes.get(k);
res.add(root);
}
}
}
return res;
}
}
运行结果: