中序+先序序列构造二叉树

最新推荐文章于 2022-10-18 14:52:44 发布

原创最新推荐文章于 2022-10-18 14:52:44 发布 · 316 阅读

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这段代码展示了如何通过先序遍历和中序遍历的序列来构造一棵二叉树。首先找到先序遍历中的根节点，然后在中序遍历中定位根节点，接着递归地构建左子树和右子树。

class Solution {
public:
TreeNode * buildTree(vector<int>& preorder, vector<int>& inorder) {
int a = preorder.size();
int b = inorder.size();
return constructree(preorder, inorder, 0, a - 1, 0,b - 1);
}
TreeNode *constructree(vector<int>& preorder, vector<int>& inorder, int prel, int prer, int inl, int inr) {
if (prel > prer) return NULL;
int tmp(preorder[prel]);
int i;
for (i = inl; i <= inr; i++) {
if (inorder[i] == tmp)
break;
}
TreeNode* newnode = new TreeNode(tmp);
newnode->left = constructree(preorder, inorder, prel + 1, prel + i - inl, inl, i - 1);
newnode->right = constructree(preorder, inorder, prel + i - inl + 1, prer, i+1, inr);
return newnode;
}
};