45 lines
1.2 KiB
C++
45 lines
1.2 KiB
C++
#include <queue>
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#include <utility>
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#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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* 958. Check Completeness of a Binary Tree
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*
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* Given the root of a binary tree, determine if it is a complete binary tree.
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* In a complete binary tree, every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the last level h.
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*/
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class Solution {
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public:
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static bool isCompleteTree(const TreeNode* r) {
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std::queue<std::pair<int, const TreeNode*>> q;
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q.emplace(1, r);
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for (int c = 1; !q.empty(); ++c) {
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const auto [v, p] = q.front();
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q.pop();
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if (v != c)
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return false;
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if (p->left) {
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q.emplace(v << 1, p->left);
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if (p->right)
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q.emplace(v << 1 | 1, p->right);
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} else if (p->right) return false;
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}
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return true;
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}
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};
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int main() {
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auto* t = new TreeNode(1, new TreeNode(2, new TreeNode(4), new TreeNode(5)), new TreeNode(3, nullptr, new TreeNode(6)));
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std::cout << Solution::isCompleteTree(t);
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return 0;
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}
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