Hacktoberfest-2022

C++/C++ Programs/Building_roads_cses(connected_components).cpp

@@ -0,0 +1,77 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define ll long long int
+#define sz(x) x.size()
+#define pb push_back
+#define pb2 pop_back
+#define ff first
+#define ss second
+#define lb lower_bound
+#define ub upper_bound
+#define bend(x) x.begin(), x.end()
+#define vi vector<ll>
+#define mapp map<ll, ll>
+#define sett set<ll>
+#define ve vector
+#define un_m unordered_map<ll, ll>
+#define f(i, a, b) for (i = a; i < b; i++)
+#define f2(i, a) for (auto i = a.begin(); i != a.end(); i++)
+#define MAXN 10000001
+
+#define mp make_pair
+#define in(t) scanf("%lld",&t)
+#define out(t) printf("%lld",t)
+
+const unsigned int moduli = 1000000007;
+
+
+ll vis[1000001];
+vi v[1000001];
+vi l;
+
+void dfs(ll n) {
+    vis[n] = 1;
+    for (auto a : v[n]) {
+        if (!vis[a]) {
+            dfs(a);
+        }
+    }
+}
+
+void sol() {
+    ll d = 0, ds, e = 0, x, n, k;
+    ll i, j, tt = 0, w = 0, t;
+    ll ans = 0, cnt = 0, sum = 0;
+    ll m;
+    cin >> n >> m;
+    f(i, 0, m) {
+        cin >> d >> e;
+        v[d].pb(e);
+        v[e].pb(d);
+    }
+    f(i, 1, n + 1) {
+        if (!vis[i])  l.pb(i), dfs(i), ans++;
+    }
+    cout << ans - 1 << endl;
+    cnt = l[0];
+    if (ans > 1)
+        f(i, 1, ans) {
+        ds = l[i];
+        cout << cnt << " " << ds << endl;
+        cnt = ds;
+    }
+
+}
+
+// driver function
+int main() {
+
+    ll tc;
+    //cin >> tc;
+    //while (tc--) {
+    sol();
+    cout << endl;
+    // }
+
+    return 0;
+}