이 제출은 이전 버전의 oj.uz에서 채점하였습니다. 현재는 제출 당시와는 다른 서버에서 채점을 하기 때문에, 다시 제출하면 결과가 달라질 수도 있습니다.
#include<bits/stdc++.h>
#define pii pair<int,int>
#define f first
#define s second
#define ll long long
using namespace std;
const int N = 2e5 + 5;
int f[N], low[N], t[N], sz[2 * N], p[N], h[N];
ll bad = 0, s[2 * N];
int n;
vector<int> adj[2 * N];
vector<pii> V[N];
map<int,int> e[N];
int find(int u) {
return (p[u] == u ? u : p[u] = find(p[u]));
}
void merge(int u, int v) {
u = find(u), v = find(v);
p[u] = v;
}
void dfs0(int u, int ID) {
f[u] = 1;
low[u] = h[u];
for(int i = 0; i < V[u].size(); i++) {
int v = V[u][i].f, id = V[u][i].s;
if(ID == id) continue;
if(f[v]) low[u] = min(low[u], h[v]);
else {
t[id] = 1;
h[v] = h[u] + 1;
dfs0(v, id);
if(low[v] < h[u]) merge(ID, id);
}
}
}
void dfs(int u, int p) {
h[u] = h[p] + 1;
sz[u] = 0;
s[u] = 0;
for(int i = 0; i < adj[u].size(); i++) {
int v = adj[u][i];
if(v == p) continue;
dfs(v, u);
s[u] += s[v] + sz[u] * sz[v];
sz[u] += sz[v];
}
if(h[u] % 2)s[u] += sz[u], sz[u]++;
if(h[u] == 3) bad += s[u];
}
void ADD(int x, int y) {
x += n;
if(e[x][y]) return;
e[x][y] = 1;
adj[x].push_back(y);
adj[y].push_back(x);
}
main() {
int m;
cin >> n >> m;
vector<pair<int,int >> e;
for(int i = 1; i <= m; i++) {
int u, v;
cin >> u >> v;
V[u].push_back({v, i});
V[v].push_back({u, i});
e.push_back({u, v});
p[i] = i;
}
dfs0(1, 0);
// for(int i = 1; i <= n; i++) V[i].clear();
for(int i = 1; i <= m; i++) {
if(!t[i]) continue;
ADD(find(i), e[i - 1].f);
ADD(find(i), e[i - 1].s);
}
for(int i = 1; i <= n; i++)
dfs(i, 0);
cout << (ll)n * (n - 1) * (n - 2) - 2 * bad;
}
컴파일 시 표준 에러 (stderr) 메시지
count_triplets.cpp: In function 'void dfs0(int, int)':
count_triplets.cpp:24:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
24 | for(int i = 0; i < V[u].size(); i++) {
| ~~^~~~~~~~~~~~~
count_triplets.cpp: In function 'void dfs(int, int)':
count_triplets.cpp:40:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
40 | for(int i = 0; i < adj[u].size(); i++) {
| ~~^~~~~~~~~~~~~~~
count_triplets.cpp: At global scope:
count_triplets.cpp:57:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
57 | main() {
| ^~~~
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