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2641.cpp
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2641.cpp
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/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
void dfs(TreeNode* node, int level, unordered_map<int, int>& levelSum) {
if (!node) return;
levelSum[level] += node->val;
dfs(node->left, level + 1, levelSum);
dfs(node->right, level + 1, levelSum);
}
void dfs2(TreeNode* node, int level, unordered_map<int, int>& levelSum) {
if (!node) return;
int leftVal = 0;
int rightVal = 0;
if (node->left) leftVal = node->left->val;
if (node->right) rightVal = node->right->val;
int valForNextLevel = levelSum[level + 1] - leftVal - rightVal;
if (node->left) node->left->val = valForNextLevel;
if (node->right) node->right->val = valForNextLevel;
dfs2(node->left, level + 1, levelSum);
dfs2(node->right, level + 1, levelSum);
}
TreeNode* replaceValueInTree(TreeNode* root) {
unordered_map<int, int> levelSum;
dfs(root, 0, levelSum);
if (root) root->val = 0;
dfs2(root, 0, levelSum);
return root;
}
};