1. Topic introduction
Design an algorithm to find the "next" node (that is, the in-order successor) of the specified node in the binary search tree.
If the specified node has no corresponding "next" node, null is returned.
Example 1:
Input: root = [2,1,3], p = 1
2
/ \
1 3
Output: 2
Example 2:
Input: root = [5,3,6,2,4,null,null,1], p = 6
5
/ \
3 6
/ \
2 4
/
1
Output: null
Source: LeetCode
Link: https://leetcode-cn.com/problems/successor-lcci The
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Two, problem-solving ideas
This question examines the middle-order traversal of the binary tree, and finds the next node of the specified node in the middle-order traversal.
Three, problem-solving code
class Solution {
public:
//二叉树的中序遍历
TreeNode* inorderSuccessor(TreeNode* root, TreeNode* p) {
stack<TreeNode*> st;
TreeNode* preNode = NULL;
while(!st.empty() || root)
{
while(root)
{
st.push(root);
root = root->left;
}
root = st.top();
st.pop();
if(p == preNode)
return root;
preNode = root;
root = root->right;
}
return NULL;
}
};Four, problem-solving results
