Submission #405397

#	Time	Username	Problem	Language	Result	Execution time	Memory
405397		aryan12	Duathlon (APIO18_duathlon)	C++17	0 / 100	1097 ms	1048580 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
#define int long long

mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());

const int N = 1e5 + 5;
vector<int> g[N];
bool vis[N];
int subtree[N], ans = 0;
int n, m;

void dfs(int node, int par) {
	subtree[node] = 1;
	vis[node] = true;
	for(int i = 0; i < g[node].size(); i++) {
		if(g[node][i] != par) {
			dfs(g[node][i], node);
			subtree[node] += subtree[g[node][i]];
		}
	}
	//cout << "node = " << node << ", subtree[node] = " << subtree[node] << "\n";
	int total = subtree[node] - 1, left = n - 1;
	for(int i = 0; i < g[node].size(); i++) {
		if(g[node][i] != par) {
			left -= subtree[g[node][i]];
			ans += (subtree[g[node][i]] * left);
		}
	}
	//cout << "node = " << node << ", ans = " << ans << "\n";
}

void Solve() {
	cin >> n >> m;
	for(int i = 1; i <= m; i++) {
		int v, u;
		cin >> v >> u;
		g[v].push_back(u);
		g[u].push_back(v);
	}
	for(int i = 1; i <= n; i++) {
		if(!vis[i]) {
			dfs(i, -1);
		}
	}
	cout << ans * 2 << "\n";
}

int32_t main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int t = 1;
	//cin >> t;
	while(t--) {
		Solve();
	}
}

/*
8 7
1 2
2 3
3 4
2 5
5 8
1 6
6 7

*/

Compilation message (stderr)

count_triplets.cpp: In function 'void dfs(long long int, long long int)':
count_triplets.cpp:16:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |  for(int i = 0; i < g[node].size(); i++) {
      |                 ~~^~~~~~~~~~~~~~~~
count_triplets.cpp:24:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |  for(int i = 0; i < g[node].size(); i++) {
      |                 ~~^~~~~~~~~~~~~~~~
count_triplets.cpp:23:6: warning: unused variable 'total' [-Wunused-variable]
   23 |  int total = subtree[node] - 1, left = n - 1;
      |      ^~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10