105. Construct Binary Tree from Preorder and Inorder Traversal

Q

A

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     struct TreeNode *left;
*     struct TreeNode *right;
* };
*/
struct TreeNode* buildTree(int* preorder, int preorderSize, int* inorder, int inorderSize) {
if (!preorderSize || !inorderSize || preorderSize != inorderSize) {
return NULL;
}

struct TreeNode *p;
p = (struct TreeNode *)malloc(sizeof(struct TreeNode));
p->val = *preorder;

int i = 0;
while(*preorder != inorder[i])
++i;
p->left = buildTree(preorder+1, i, inorder, i);
p->right = buildTree(preorder+i+1, preorderSize-i-1, inorder+i+1, inorderSize-i-1);

return p;
}