Create Construct_binary_tree.cpp

C++/Construct_binary_tree.cpp

@@ -0,0 +1,55 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+struct Node
+{
+    int key;
+    struct Node *left;
+    struct Node *right;
+    Node(int k)
+    {
+        key = k;
+        left = right = NULL;
+    }
+};
+
+void inorder(Node *root)
+{
+    if (root != NULL)
+    {
+        inorder(root->left);
+        cout << root->key << " ";
+        inorder(root->right);
+    }
+}
+
+int preIndex = 0;
+Node *cTree(int in[], int pre[], int is, int ie)
+{
+    if (is > ie)
+        return NULL;
+    Node *root = new Node(pre[preIndex++]);
+
+    int inIndex;
+    for (int i = is; i <= ie; i++)
+    {
+        if (in[i] == root->key)
+        {
+            inIndex = i;
+            break;
+        }
+    }
+    root->left = cTree(in, pre, is, inIndex - 1);
+    root->right = cTree(in, pre, inIndex + 1, ie);
+    return root;
+}
+
+int main()
+{
+
+    int in[] = {20, 10, 40, 30, 50};
+    int pre[] = {10, 20, 30, 40, 50};
+    int n = sizeof(in) / sizeof(in[0]);
+    Node *root = cTree(in, pre, 0, n - 1);
+    inorder(root);
+}