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144. 最长异或值路径
https://www.acwing.com/problem/content/submission/code_detail/8019318/
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AcWing/144/144.cpp
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68
AcWing/144/144.cpp
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#include <bits/stdc++.h>
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using namespace std;
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int n, u, v, w, a[100005], ans;
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vector<pair<int, int>> g[100005];
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struct node {
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int size;
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node* next[2];
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~node() {
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for (auto& i : next) {
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delete i;
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}
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}
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};
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void dfs(int u, int fa, int sum) {
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a[u] = sum;
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for (auto i : g[u]) {
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if (i.first != fa) {
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dfs(i.first, u, sum ^ i.second);
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}
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}
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}
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void insert(node* root, int x, int b) {
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if (!x) {
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root->size++;
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return;
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}
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if (root->next[(x >> b) & 1] == nullptr) root->next[(x >> b) & 1] = new node();
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insert(root->next[(x >> b) & 1], x - (((x >> b) & 1) << b), b - 1);
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}
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int query(node* root, int x) {
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int res = 0;
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for (int i = 31; i >= 0; i--) {
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if (root == nullptr) break;
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if (root->next[!((x >> i) & 1)] != nullptr) {
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res += 1 << i;
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root = root->next[!((x >> i) & 1)];
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} else {
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root = root->next[(x >> i) & 1];
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}
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}
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return res;
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}
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int main() {
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node* root = new node();
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cin >> n;
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for (int i = 1; i < n; i++) {
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cin >> u >> v >> w;
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g[u].push_back(make_pair(v, w));
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g[v].push_back(make_pair(u, w));
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}
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dfs(0, -1, 0);
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for (int i = 0; i < n; i++) {
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insert(root, a[i], 31);
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}
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for (int i = 0; i < n; i++) {
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ans = max(ans, query(root, a[i]));
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}
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cout << ans << endl;
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return 0;
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}
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