51 problems solved

CSES - CSES Problem Set/Dynamic_Range_Minimum_Queries.cpp

@@ -0,0 +1,68 @@
+//  Dynamic Range Minimum Queries
+
+#include<bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+void update(int k, ll x, vector<ll> &tree, int n) {
+    k--;
+    k += n;
+    tree[k] = x;
+    k /= 2;
+    for (; k >= 1; k /= 2) {
+        tree[k] = min(tree[2*k], tree[2*k + 1]);
+    }
+}
+
+vector<ll> construct(vector<ll> &input) {
+    int n = input.size();
+    vector<ll> out(2*n);
+    for (int i{}; i < n; i++) {
+        out[i+n] = input[i];
+    }
+    for (int i = n - 1; i >= 1; i--) {
+        out[i] = min(out[2*i], out[2*i + 1]);
+    }
+    return out;
+}
+
+ll query(vector<ll> &tree, int a, int b, int n) {
+    a += n; b += n;
+    ll s = INT_MAX;
+    while (a <= b) {
+        if (a % 2 == 1) {
+            s = min(s, tree[a]);
+            a++;
+        }
+        if (b % 2 == 0) {
+            s = min(s, tree[b]);
+            b--;
+        }
+        a /= 2;
+        b /= 2;
+    }
+    return s;
+}
+
+int main() {
+    int n, q; cin >> n >> q;
+    vector<ll> in(n);
+    for (auto &e: in) cin >> e;
+    auto seg = construct(in);
+    for (int i{}; i < q; i++) {
+        int t; cin >> t;
+        if (t == 1) {
+            int k;
+            ll u;
+            cin >> k >> u;
+            update(k, u, seg, n);
+        }
+        if (t == 2) {
+            int a, b; cin >> a >> b;
+            a--; b--;
+            cout << query(seg, a, b, n) << endl;
+        }
+    }
+    return 0;
+}

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;
+}