diff options
Diffstat (limited to 'construct_bt_io_po.c')
-rw-r--r-- | construct_bt_io_po.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/construct_bt_io_po.c b/construct_bt_io_po.c new file mode 100644 index 0000000..9c145eb --- /dev/null +++ b/construct_bt_io_po.c @@ -0,0 +1,37 @@ +// 106. Construct Binary Tree from Inorder and Postorder Traversal +#include <stdint.h> +#include <stdlib.h> + +/* + * given two integer arrays 'inorder' and 'postorder', where 'inorder' is the + * inorder traversal of a binary tree, and 'postorder' is the postorder + * traversal of the same tree, construct and return the binary tree. + */ + +struct TreeNode { + int val; + struct TreeNode *left; + struct TreeNode *right; +}; + +struct TreeNode *buildTree(int *inorder, int inorder_size, int *postorder, + int postorder_size) { + if (inorder_size == 0) + return NULL; + struct TreeNode *root = (struct TreeNode *)malloc(sizeof(struct TreeNode)); + root->val = postorder[postorder_size - 1]; + root->left = NULL; + root->right = NULL; + if (postorder_size == 1) + return root; + uint16_t i; + for (i = 0; i < inorder_size; i++) + if (inorder[i] == root->val) + break; + int l_size = i; + root->left = buildTree(inorder, l_size, postorder, l_size); + int r_size = postorder_size - 1 - l_size; + root->right = + buildTree(&inorder[1 + l_size], r_size, &postorder[l_size], r_size); + return root; +} |