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AT2376 [AGC014D] Black and White Tree

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https://www.luogu.com.cn/record/59261217
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Baoshuo Ren 2021-10-06 10:06:44 +08:00 committed by Baoshuo Ren
parent 2ae880089e
commit 02ed7be7c2
Signed by: baoshuo
GPG Key ID: 70F90A673FB1AB68
1 changed files with 17 additions and 25 deletions
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42
Luogu/problem/AT2376/AT2376.cpp
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@ -2,40 +2,32 @@
using namespace std; using namespace std;
int n, u, v;
vector<int> g[100005]; vector<int> g[100005];
int n, x, y, s[100005]; bool flag, vis[100005];
bool flag;
void dfs(int u, int p) { void dfs(int u, int f) {
s[u] = 1; if (flag) return;
int t = 0; for (int i : g[u]) {
for (int i = 0; i < g[u].size(); i++) { if (i != f) dfs(i, u);
if (g[u][i] != p) { }
dfs(g[u][i], u); if (!vis[u]) {
t += s[g[u][i]]; if (f == -1 || vis[f]) {
s[u] ^= s[g[u][i]]; flag = true;
} else {
vis[f] = vis[u] = true;
} }
} }
if (t > 1) flag = true;
} }
int main() { int main() {
cin >> n; cin >> n;
for (int i = 1; i < n; i++) { for (int i = 1; i < n; i++) {
cin >> x >> y; cin >> u >> v;
g[x].push_back(y); g[u].push_back(v);
g[y].push_back(x); g[v].push_back(u);
}
if (n & 1) {
cout << "First" << endl;
return 0;
}
dfs(1, 0);
if (flag) {
cout << "First" << endl;
}
else {
cout << "Second" << endl;
} }
dfs(1, -1);
cout << (flag ? "First" : "Second") << endl;
return 0; return 0;
} }