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OI-codes/AcWing/1183/1183.cpp

63 lines
1.2 KiB
C++

#include <iostream>
#include <array>
#include <stack>
#include <vector>
using std::cin;
using std::cout;
using std::endl;
const int N = 10005;
int ans;
std::array<std::vector<int>, N> g;
// Tarjan
int root;
std::array<int, N> dfn;
int cnt, low[N];
int dcc_cnt, id[N];
std::stack<int> st;
void tarjan(int);
int main() {
int n, m;
while (cin >> n >> m, n || m) {
ans = dcc_cnt = cnt = 0;
dfn.fill(0);
g.fill({});
for (int i = 1; i <= m; i++) {
int a, b;
cin >> a >> b;
g[a + 1].push_back(b + 1);
g[b + 1].push_back(a + 1);
}
for (int i = 1; i <= n; i++) {
if (!dfn[i]) {
root = i;
dcc_cnt++;
tarjan(i);
}
}
cout << ans + dcc_cnt - 1 << endl;
}
return 0;
}
void tarjan(int u) {
dfn[u] = low[u] = ++cnt;
int size = 0;
for (int v : g[u]) {
if (!dfn[v]) {
tarjan(v);
low[u] = std::min(low[u], low[v]);
if (low[v] >= dfn[u]) size++;
} else {
low[u] = std::min(low[u], dfn[v]);
}
}
if (u != root) size++;
ans = std::max(ans, size);
}