#include "bits/stdc++.h"
#define int long long
using namespace std;
const int MAXN = 4e5 + 10;
vector<int> adj[MAXN];
vector<int> rst[MAXN]; // round-square tree
int n, m, cur;
int tin[MAXN], low[MAXN], vis[MAXN];
stack<int> stk;
int nxt;
int ans = 0;
void dfs(int node, int prv) {
vis[node] = 1;
tin[node] = ++cur;
low[node] = tin[node];
stk.push(node);
for(int x: adj[node]) {
if(x != prv) {
if(!vis[x]) {
dfs(x, node);
low[node] = min(low[node], low[x]);
if(low[x] >= tin[node]) {
while(1) {
int u = stk.top();
stk.pop();
rst[u].push_back(nxt);
rst[nxt].push_back(u);
if(u == x) break;
}
rst[node].push_back(nxt);
rst[nxt].push_back(node);
nxt++;
}
}
else {
low[node] = min(low[node], tin[x]);
}
}
}
}
int w[MAXN];
int calc(int node, int prv) {
int ret = (node <= n);
vector<int> vt;
for(int x: rst[node]) {
if(x != prv) {
int v = calc(x, node);
ret += v;
vt.push_back(v);
}
}
vt.push_back(n - ret);
int con = (node <= n ? 2 * (n-1) : 0);
int ps = 0;
for(int x: vt) {
con += ps * x * 2;
ps += x;
}
ans += con * w[node];
return ret;
}
int32_t main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
if(n == m) {
cout << n * (n-1) * (n-2) << "\n";
}
else {
cout << n * (n-1) * (n-2) / 3 << "\n";
}
return 0;
for(int i=1; i<=m; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
nxt = n+1;
dfs(1, -1);
m = nxt-1 - n;
for(int i=1; i<=n; i++) w[i] = -1;
for(int i=n+1; i<=n+m; i++) w[i] = rst[i].size();
calc(1, -1);
cout << ans << '\n';
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
11 ms |
19028 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
11 ms |
19028 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
10 ms |
19028 KB |
Output is correct |
2 |
Correct |
11 ms |
19120 KB |
Output is correct |
3 |
Incorrect |
9 ms |
19128 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
10 ms |
19124 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
12 ms |
19008 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
11 ms |
19120 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
12 ms |
19076 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
11 ms |
19028 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
11 ms |
19028 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |