Add a bunch of other problems.

Some are not finished...

Codeforces Round 991 (Div. 3)/C. Uninteresting Number.cpp

@@ -0,0 +1,115 @@
+/* Problem URL: https://codeforces.com/contest/2050/problem/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 (size_t i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (size_t 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;
+}
+
+bool vis[9];
+
+void pos(int mod, int two, int three)
+{
+    vis[mod] = true;
+
+
+    if (!vis[(mod + 2) % 9] && two > 0) {
+        pos((mod + 2) % 9, two - 1, three);
+    }
+    if (!vis[(mod + 6) % 9] && three > 0) {
+        pos((mod + 6) % 9, two, three - 1);
+    }
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        string a;
+        cin >> a;
+
+        ll total = 0;
+        ll three = 0;
+        ll two = 0;
+        repv(i, a) {
+            total += i - '0';
+            if (i == '3') {
+                three++;
+            } else if (i == '2') {
+                two++;
+            }
+        }
+
+        memset(vis, 0, sizeof(vis));
+        pos(total % 9, two, three);
+
+        cout << (vis[0] ? "YES\n" : "NO\n");
+    }
+}