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| class Solution {
public TreeNode bstFromPreorder(int[] preorder) {
return bstFromPreorder(preorder, 0, preorder.length - 1);
}
private TreeNode bstFromPreorder(int[] preorder, int rootIndex, int endIndex) {
if (rootIndex > endIndex) {
return null;
}
TreeNode root = new TreeNode(preorder[rootIndex]);
if (rootIndex == endIndex) {
return root;
}
int rightStartIndex = rootIndex + 1;
while (rightStartIndex < preorder.length && preorder[rightStartIndex] < preorder[rootIndex]) {
rightStartIndex++;
}
root.left = bstFromPreorder(preorder, rootIndex + 1, rightStartIndex - 1);
root.right = bstFromPreorder(preorder, rightStartIndex, endIndex);
return root;
}
}
|
References
1008. Construct Binary Search Tree from Preorder Traversal