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JianZhi004.java
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JianZhi004.java
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import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
/**
* @ProjectName: LeetCode
* @Author: XinyuLiu
* @Description:
*/
public class JianZhi004 {
public class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) { val = x; }
}
//1.递归
public TreeNode buildTree(int[] preorder, int[] inorder) {
if(preorder.length == 0 || inorder.length == 0) return null;
int root = preorder[0];
TreeNode node = new TreeNode(root);
for (int i = 0; i < inorder.length; i++) {
if(inorder[i] == root){
node.left = buildTree(Arrays.copyOfRange(preorder,1,i + 1),Arrays.copyOfRange(inorder,0,i));
node.right = buildTree(Arrays.copyOfRange(preorder,i + 1,preorder.length),Arrays.copyOfRange(inorder,i + 1,inorder.length));
}
}
return node;
}
}