Add a bunch of other problems.

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Codeforces Round 975 (Div. 1)/C. Tree Pruning.cpp

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+/* Problem URL: https://codeforces.com/problemset/problem/2018/C */
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        vvi graph(n);
+
+        rep(i, n - 1) {
+            int a, b;
+            cin >> a >> b;
+            a--, b--;
+
+            graph[a].push_back(b);
+            graph[b].push_back(a);
+        }
+
+        if (n > 1) {
+            n = 1 << (32 - __builtin_clz(n));
+        }
+
+        vi seg(n * 2);
+
+        function<void(int, int, int, int, int)> update = [&](int i, int l, int r, int tl, int tr) {
+            if (l > tr || r < tl) {
+                return;
+            }
+
+            if (l >= tl && r <= tr) {
+                seg[i]++;
+                return;
+            }
+
+            int mid = (l + r) / 2;
+            update(i * 2, l, mid, tl, tr );
+            update(i * 2 + 1, mid + 1, r, tl, tr);
+        };
+
+        auto get = [&](int i) {
+            int ans = 0;
+            for (i = (i + n); i > 0; i /= 2) {
+                ans += seg[i];
+            }
+
+            return ans;
+        };
+
+        function<int(int, int, int)> dfs = [&](int i, int p, int d) {
+            int ans = d;
+
+            repv(j, graph[i]) {
+                if (j == p) {
+                    continue;
+                }
+
+                rmax(ans, dfs(j, i, d + 1));
+            }
+
+            update(1, 0, n - 1, 0, d - 1);
+            update(1, 0, n - 1, ans + 1, n - 1);
+            return ans;
+        };
+
+        dfs(0, 0, 0);
+
+        int ans = INT32_MAX >> 1;
+
+        rep(i, n) {
+            rmin(ans, get(i));
+        }
+
+        cout << ans << '\n';
+    }
+}