题解 | #将二叉搜索树变为双向链表#

/** public class TreeNode { int val = 0; TreeNode left = null; TreeNode right = null;

public TreeNode(int val) {
    this.val = val;

}

} */ public class Solution {

public TreeNode prev=null;
//中序遍历
public void ConvertChild(TreeNode pCur){
    if(pCur==null) {
        return;
    }
    ConvertChild(pCur.left);
    
    //处理每个节点，将该节点的左右指向改变
    pCur.left=prev;
    if(prev!=null){
        prev.right=pCur;
    }
    prev=pCur;
    
    ConvertChild(pCur.right);
    
    
}
public TreeNode Convert(TreeNode pRootOfTree) {
    if(pRootOfTree ==null) return null;
    ConvertChild(pRootOfTree);
    
    //找到链表的头节点
    TreeNode head=pRootOfTree;
    while(head.left !=null){
        head=head.left;
    }
    return head;
}

}