37 lines
895 B
C++
37 lines
895 B
C++
#include <iostream>
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struct TreeNode {
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int val;
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TreeNode* left;
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TreeNode* right;
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explicit TreeNode(int x, TreeNode* left = nullptr, TreeNode* right = nullptr) : val(x), left(left), right(right) {}
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};
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/**
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* 面试题 04.06. Successor LCCI
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* Write an algorithm to find the "next" node (i.e., in-order successor) of a given node in a binary search tree.
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* Return null if there's no "next" node for the given node.
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*/
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class Solution {
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public:
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static TreeNode* inorderSuccessor(TreeNode* root, TreeNode* p) {
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if (!root || !p)
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return nullptr;
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// Target value: p->val;
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TreeNode* ret = nullptr;
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for (auto* ptr = root; ptr; ) {
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if (ptr->val == p->val) {
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for (ptr = ptr->right; ptr && ptr->left; ptr = ptr->left);
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return ptr ? ptr : ret;
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} else if (ptr->val < p->val) {
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ptr = ptr->right;
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} else {
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ret = ptr;
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ptr = ptr->left;
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}
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}
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return ret;
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}
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};
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