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- #include <iostream>
- #include <vector>
- #include <algorithm>
- using namespace std;
- const int maxn = 1e5 + 10;
- vector<int> graph[maxn];
- bool visited[maxn];
- int size_of_island;
- void dfs(int node) {
- visited[node] = true;
- size_of_island++;
- for(int i = 0; i < (int) graph[node].size(); i++) {
- int neighbour = graph[node][i];
- if(!visited[neighbour]) {
- dfs(neighbour);
- }
- }
- }
- int main() {
- ios_base::sync_with_stdio(false);
- int n, m;
- cin >> n >> m;
- for(int i = 0; i < m; i++) {
- int a, b;
- cin >> a >> b;
- graph[a].push_back(b);
- graph[b].push_back(a);
- }
- for(int i = 0; i < n; i++) {
- visited[i] = false;
- }
- long long res = 0;
- for(int i = 0; i < n; i++) {
- if(!visited[i]) {
- size_of_island = 0;
- dfs(i);
- res += size_of_island * (n - size_of_island);
- }
- }
- cout << res / 2 << endl;
- return 0;
- }
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