47 lines
1.1 KiB
C++
47 lines
1.1 KiB
C++
#include <functional>
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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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* 129. Sum Root to Leaf Numbers
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*
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* You are given the root of a binary tree containing digits from 0 to 9 only.
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* Each root-to-leaf path in the tree represents a number.
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* For example, the root-to-leaf path 1 -> 2 -> 3 represents the number 123.
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* Return the total sum of all root-to-leaf numbers. Test cases are generated so that the answer will fit in a 32-bit integer.
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* A leaf node is a node with no children.
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*/
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class Solution {
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public:
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static int sumNumbers(const TreeNode* root) {
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if (!root)
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return 0;
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int stack[16]{root->val}, ptr = 0, ans = 0;
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std::function<void(const TreeNode*)> dfs = [&](const TreeNode* r) {
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if (!r->left && !r->right) {
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ans += stack[ptr];
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return;
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}
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++ptr;
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if (r->left) {
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stack[ptr] = 10 * stack[ptr - 1] + r->left->val;
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dfs(r->left);
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}
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if (r->right) {
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stack[ptr] = 10 * stack[ptr - 1] + r->right->val;
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dfs(r->right);
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}
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--ptr;
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};
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dfs(root);
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return ans;
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}
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};
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