add: 220714

cpp/2207/220714.cpp

@@ -0,0 +1,36 @@
+#include <vector>
+#include <algorithm>
+
+struct TreeNode {
+	int val;
+	TreeNode* left;
+	TreeNode* right;
+	explicit TreeNode(int x, TreeNode* left = nullptr, TreeNode* right = nullptr) : val(x), left(left), right(right) {}
+};
+
+/**
+ * 105. Construct Binary Tree from Preorder and Inorder Traversal
+ * Given two integer arrays preorder and inorder where preorder is the preorder traversal of a binary tree and inorder is the inorder traversal of the same tree, construct and return the binary tree.
+ */
+
+class Solution {
+private:
+	TreeNode* buildTree(std::vector<int>::const_iterator preBegin, std::vector<int>::const_iterator preEnd, std::vector<int>::const_iterator inBegin, std::vector<int>::const_iterator inEnd) {
+		if (preBegin == preEnd)
+			return nullptr;
+		if (std::next(preBegin) == preEnd)
+			return new TreeNode(*preBegin);
+		auto midIt = std::find(inBegin, inEnd, *preBegin);
+		auto lenL = std::distance(inBegin, midIt);
+		return new TreeNode(
+			*preBegin,
+			buildTree(preBegin + 1, preBegin + 1 + lenL, inBegin, midIt),
+			buildTree(preBegin + 1 + lenL, preEnd, midIt + 1, inEnd)
+		);
+	}
+
+public:
+	TreeNode* buildTree(const std::vector<int>& preorder, const std::vector<int>& inorder) {
+		return buildTree(preorder.begin(), preorder.end(), inorder.begin(), inorder.end());
+	}
+};