Leetcode #106

gistfile1.txt

import java.util.Arrays;
public class Solution {
    public TreeNode buildTree(int[] inorder, int[] postorder) {
        int in_len = inorder.length;
        int post_len = postorder.length;
        if(post_len == 0)
            return null;
        TreeNode root=new TreeNode(postorder[post_len-1]);
        int position=in_len-1;
        while(inorder[position] != postorder[post_len-1]){
            position--;
        }
        if(position<in_len-1){
            int[] inorder_right_sub = Arrays.copyOfRange(inorder, position+1, in_len);
            int[] post_right_sub = Arrays.copyOfRange(postorder, position, post_len-1);
            root.right = buildTree(inorder_right_sub, post_right_sub);
        }
        if(position>0){
            int[] inorder_left_sub = Arrays.copyOfRange(inorder, 0, position);
            int[] post_left_sub = Arrays.copyOfRange(postorder, 0, position);
            root.left = buildTree(inorder_left_sub, post_left_sub);
        }
        return root;
    }
    
}