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OI-codes/AtCoder/ABC309/D/D.cpp

59 lines
1011 B
C++

#include <iostream>
#include <algorithm>
#include <queue>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 3e5 + 5;
int n1, n2, m, dist1[N], dist2[N];
bool vis[N];
std::vector<int> g[N];
void bfs(int s, int* dist) {
std::queue<int> q;
q.emplace(s);
vis[s] = true;
while (!q.empty()) {
int u = q.front();
q.pop();
for (int v : g[u]) {
if (vis[v]) continue;
vis[v] = true;
dist[v] = dist[u] + 1;
q.emplace(v);
}
}
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n1 >> n2 >> m;
for (int i = 1, u, v; i <= m; i++) {
cin >> u >> v;
g[u].emplace_back(v);
g[v].emplace_back(u);
}
bfs(1, dist1);
bfs(n1 + n2, dist2);
cout << *std::max_element(dist1 + 1, dist1 + 1 + n1)
+ *std::max_element(dist2 + n1 + 1, dist2 + n1 + n2 + 1) + 1
<< endl;
return 0;
}