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| #include <bits/stdc++.h>
const int N = 5000 + 10;
using namespace std;
int cnt;
int head[N];
struct edge
{
int u, v, next;
} e[N << 1];
void add(int u, int v)
{
e[++cnt].u = u;
e[cnt].v = v;
e[cnt].next = head[u];
head[u] = cnt;
}
vector<int> vec[N];
int n, m, ans[N], k[N], x, y, dep, vis[N], from[N], to[N];
void dfs(int u, int fa)
{
if (vis[u])
return;
vis[u] = 1;
k[++dep] = u;
for (int i = 0; i < vec[u].size(); i++)
{
int v = vec[u][i];
if (v == fa)
continue;
if ((v == y && u == x) || (v == x && u == y))
continue;
dfs(v, u);
}
}
bool check()
{
for (int i = 1; i <= n; i++)
{
if (k[i] == ans[i])
continue;
if (k[i] > ans[i])
return false;
else
return true;
}
}
void change()
{
for (int i = 1; i <= n; i++)
ans[i] = k[i];
}
void dfs2(int u, int fa)
{
if (vis[u])
return;
vis[u] = 1;
ans[++dep] = u;
for (int i = 0; i < vec[u].size(); i++)
{
int v = vec[u][i];
if (v == fa)
continue;
dfs2(v, u);
}
}
int main()
{
int u, v;
scanf("%d%d", &n, &m);
for (int i = 1; i <= m; i++)
{
scanf("%d%d", &u, &v);
vec[u].push_back(v);
vec[v].push_back(u);
add(u, v);
add(v, u);
}
for (int i = 1; i <= n; i++)
sort(vec[i].begin(), vec[i].end());
if (n == m)
{
for (int i = 1; i <= cnt; i += 2)
{
dep = 0;
x = e[i].u;
y = e[i].v;
memset(vis, 0, sizeof(vis));
dfs(1, -1);
if (dep < n)
continue;
if (ans[1] == 0)
change();
else if (check())
change();
}
for (int i = 1; i <= n; i++)
printf("%d ", ans[i]);
}
else
{
dfs2(1, -1);
for (int i = 1; i <= n; i++)
printf("%d ", ans[i]);
}
return 0;
}
|
