51 problems solved

CSES - CSES Problem Set/Graph_Algorithms/Building_Roads.cpp

@@ -0,0 +1,40 @@
+//  Building Roads
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+void dfs(vector<vector<int>> &g, int s, vector<bool> &v) {
+    v[s] = true;
+    for (auto e: g[s]) {
+        if (!v[e]) dfs(g, e, v);
+    }
+}
+
+
+int main() {
+    int n, m; cin >> n >> m;
+    vector<vector<int>> g(n);
+    for (int i{}; i < m; i++) {
+        int a, b;
+        cin >> a >> b;
+        a--; b--;
+        g[a].push_back(b);
+        g[b].push_back(a);
+    }
+    int count = -1;
+    vector<pair<int, int>> roads;
+    vector<bool> v(n);
+    for (int i{}; i < n; i++) {
+        if (v[i]) continue;
+        count ++;
+        dfs(g, i, v);
+        if (i > 0) roads.push_back({i, i - 1});
+    }
+
+    cout << count << endl;
+    for (auto [x, y]: roads) {
+        cout << x+1 << " " << y + 1 << endl;
+    }
+    return 0;
+}

CSES - CSES Problem Set/Graph_Algorithms/Counting_Rooms.cpp

@@ -0,0 +1,44 @@
+//  Counting Rooms
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+void dfs(vector<vector<vector<pair<int, int>>>> &m, pair<int, int> s,  vector<vector<bool>> &v) {
+    v[s.first][s.second] = true;
+    for (auto e: m[s.first][s.second]) {
+        if (!v[e.first][e.second]) dfs(m, e, v);
+    }
+}
+
+int main() {
+    int n, m; cin >> n >> m;
+//    map<pair<int, int>, vector<pair<int, int>>> map1;
+    vector<vector<vector<pair<int, int>>>> map1(n, vector<vector<pair<int, int>>>(m));
+    vector<string> in;
+    for (int i{}; i < n; i++) {
+        string s; cin >> s; in.push_back(s);
+    }
+    for (int i{}; i < n; i++) {
+        for (int j{}; j < m; j++) {
+            if (in[i][j] == '#') continue;
+            if (i > 0 && in[i-1][j] == '.') map1[i][j].push_back({i-1, j});
+            if (i < n - 1 && in[i+1][j] == '.') map1[i][j].push_back({i+1, j});
+            if (j > 0 && in[i][j-1] == '.') map1[i][j].push_back({i, j-1});
+            if (j < m - 1 && in[i][j+1] == '.') map1[i][j].push_back({i, j+1});
+        }
+    }
+//    set<pair<int, int>> v;
+    vector<vector<bool>> v(n, vector<bool>(m, false));
+    int count = 0;
+    for (int i{}; i < n; i++) {
+        for (int j{}; j < m; j++) {
+            if (in[i][j] == '#') continue;
+            if (v[i][j]) continue;
+            count++;
+            dfs(map1, {i, j}, v);
+        }
+    }
+    cout << count << endl;
+    return 0;
+}