Solved a bunch of problems

90 files changed, 2703 insertions, 23 deletions

diff --git a/contests/Round#853/A/main b/contests/Round#853/A/main
new file mode 100755
index 0000000..8a4dd75
--- /dev/null
+++ b/contests/Round#853/A/main
diff --git a/contests/Round#853/A/main.cpp b/contests/Round#853/A/main.cpp
new file mode 100755
index 0000000..48a23d2
--- /dev/null
+++ b/contests/Round#853/A/main.cpp
@@ -0,0 +1,116 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+using ll = long long;
+using pi = pair<int, int>;
+using vpi = vector<pi>;
+using vi = vector<int>;
+using vll = vector<long long>;
+using mpii = map<int, int>;
+using mpll = map<ll, ll>;
+using db = long double;
+
+#define pb push_back
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+#define lb lower_bound
+#define ub upper_bound
+
+const int MOD = (int)1e9 + 7;
+const db PI = acos((db)-1);
+const int dx[4]{1, 0, -1, 0};
+const int dy[4]{0, 1, 0, -1};
+
+// pretty printing
+template <typename K, typename V> void printm(const map<K, V> &mp) {
+  cerr << "{" << endl;
+  for (auto p : mp) {
+    cerr << "  { " << p.first << " : " << p.second << " }\n";
+  }
+  cerr << "}" << endl;
+}
+template <typename T> void printv(const vector<T> &v) {
+  cerr << "[";
+  for (int i = 0; i < v.size(); i++) {
+    if (i == v.size() - 1) {
+      cerr << v[i];
+    } else {
+      cerr << v[i] << ", ";
+    }
+  }
+  cerr << "]\n";
+}
+
+template <typename T> void printvv(const vector<vector<T>> &v) {
+  cerr << "[\n";
+  for (auto &vec : v) {
+    cout << "  ";
+    printv(vec);
+  }
+  cerr << "]\n";
+}
+void print() { cerr << "\n"; }
+
+template <typename T, typename... TS> void print(T val, TS... vals) {
+  cerr << val << " ";
+  print(vals...);
+}
+
+/* stuff you should look for:
+  ---------------------------
+   * special cases (n=1?)
+   * int overflow, array bounds
+   * do smth instead of nothing and stay organized
+   * WRITE STUFF DOWN
+   * DON'T GET STUCK ON ONE APPROACH
+ */
+
+bool isGood(vi &v) {
+  int n = v.size();
+  int ans = __gcd(v[0], v[1]);
+  for (int i = 2; i < n; i++) {
+    ans = __gcd(ans, v[i]);
+  }
+  return ans <= n;
+}
+
+bool isBeautiful(vi &v) {
+  for (int i = 0; i <= v.size() - 2; i++) {
+    vi newVec = vector<int>(v.begin(), v.begin() + i + 2);
+    if (!isGood(newVec)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+void solve() {
+  int n;
+  cin >> n;
+  vi v(n);
+  for (auto &x : v)
+    cin >> x;
+  if (isBeautiful(v)) {
+    cout << "Yes" << '\n';
+    return;
+  } else {
+    sort(all(v));
+    do {
+      if (isBeautiful(v)) {
+        cout << "Yes" << '\n';
+        return;
+      }
+    } while (next_permutation(all(v)));
+  }
+  cout << "No" << '\n';
+}
+
+int main() {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int tt;
+  cin >> tt;
+  while (tt--) {
+    solve();
+  }
+}
diff --git a/contests/Round#853/A/main_input0.txt b/contests/Round#853/A/main_input0.txt
new file mode 100644
index 0000000..e0ee38b
--- /dev/null
+++ b/contests/Round#853/A/main_input0.txt
@@ -0,0 +1,13 @@
+6
+2
+3 6
+3
+1 2 4
+3
+3 6 1
+3
+15 35 21
+4
+35 10 35 14
+5
+1261 227821 143 4171 1941
diff --git a/contests/Round#853/A/main_output0.txt b/contests/Round#853/A/main_output0.txt
new file mode 100644
index 0000000..14668ea
--- /dev/null
+++ b/contests/Round#853/A/main_output0.txt
@@ -0,0 +1,6 @@
+No
+Yes
+Yes
+No
+Yes
+Yes
diff --git a/contests/Round#853/B/\ b/contests/Round#853/B/\
new file mode 100644
index 0000000..499f739
--- /dev/null
+++ b/contests/Round#853/B/\
@@ -0,0 +1,105 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+using ll = long long;
+using pi = pair<int, int>;
+using vpi = vector<pi>;
+using vi = vector<int>;
+using vll = vector<long long>;
+using mpii = map<int, int>;
+using mpll = map<ll, ll>;
+using db = long double;
+
+#define pb push_back
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+#define lb lower_bound
+#define ub upper_bound
+
+const int MOD = (int)1e9 + 7;
+const db PI = acos((db)-1);
+const int dx[4]{1, 0, -1, 0};
+const int dy[4]{0, 1, 0, -1};
+
+// pretty printing
+template <typename K, typename V> void printm(const map<K, V> &mp) {
+  cerr << "{" << endl;
+  for (auto p : mp) {
+    cerr << "  { " << p.first << " : " << p.second << " }\n";
+  }
+  cerr << "}" << endl;
+}
+template <typename T> void printv(const vector<T> &v) {
+  cerr << "[";
+  for (int i = 0; i < v.size(); i++) {
+    if (i == v.size() - 1) {
+      cerr << v[i];
+    } else {
+      cerr << v[i] << ", ";
+    }
+  }
+  cerr << "]\n";
+}
+
+template <typename T> void printvv(const vector<vector<T>> &v) {
+  cerr << "[\n";
+  for (auto &vec : v) {
+    cout << "  ";
+    printv(vec);
+  }
+  cerr << "]\n";
+}
+void print() { cerr << "\n"; }
+
+template <typename T, typename... TS> void print(T val, TS... vals) {
+  cerr << val << " ";
+  print(vals...);
+}
+
+/* stuff you should look for:
+  ---------------------------
+   * special cases (n=1?)
+   * int overflow, array bounds
+   * do smth instead of nothing and stay organized
+   * WRITE STUFF DOWN
+   * DON'T GET STUCK ON ONE APPROACH
+ */
+
+bool isPalindrome(string &s) { return string(all(s)) == string(rall(s)); }
+
+void solve() {
+  int n;
+  cin >> n;
+  string s;
+  cin >> s;
+  if (isPalindrome(s)) {
+    cout << "Yes" << '\n';
+  } else {
+    vector<bool> pal(n);
+    if (n & 1)
+      pal[n / 2] = 1;
+    for (int i = 0; i < n / 2; i++) {
+      pal[i] = pal[n - i - 1] = s[i] == s[n - i - 1];
+    }
+    pal.erase(unique(all(pal)));
+    // string haystack = "";
+    // for (int i = 0; i < n / 2; i++) {
+    //   haystack += (pal[i] ? "R" : "W");
+    // }
+    // if (regex_match(haystack, regex("WR+W"))) {
+    //   cout << "No" << '\n';
+    // } else {
+    //   cout << "Yes" << '\n';
+    // }
+  }
+}
+
+int main() {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int tt;
+  cin >> tt;
+  while (tt--) {
+    solve();
+  }
+}
diff --git a/contests/Round#853/B/main b/contests/Round#853/B/main
new file mode 100755
index 0000000..71f1358
--- /dev/null
+++ b/contests/Round#853/B/main
diff --git a/contests/Round#853/B/main.cpp b/contests/Round#853/B/main.cpp
new file mode 100755
index 0000000..12517e2
--- /dev/null
+++ b/contests/Round#853/B/main.cpp
@@ -0,0 +1,107 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+using ll = long long;
+using pi = pair<int, int>;
+using vpi = vector<pi>;
+using vi = vector<int>;
+using vll = vector<long long>;
+using mpii = map<int, int>;
+using mpll = map<ll, ll>;
+using db = long double;
+
+#define pb push_back
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (x).rbegin(), (x).rend()
+#define lb lower_bound
+#define ub upper_bound
+
+const int MOD = (int)1e9 + 7;
+const db PI = acos((db)-1);
+const int dx[4]{1, 0, -1, 0};
+const int dy[4]{0, 1, 0, -1};
+
+// pretty printing
+template <typename K, typename V> void printm(const map<K, V> &mp) {
+  cerr << "{" << endl;
+  for (auto p : mp) {
+    cerr << "  { " << p.first << " : " << p.second << " }\n";
+  }
+  cerr << "}" << endl;
+}
+template <typename T> void printv(const vector<T> &v) {
+  cerr << "[";
+  for (int i = 0; i < v.size(); i++) {
+    if (i == v.size() - 1) {
+      cerr << v[i];
+    } else {
+      cerr << v[i] << ", ";
+    }
+  }
+  cerr << "]\n";
+}
+
+template <typename T> void printvv(const vector<vector<T>> &v) {
+  cerr << "[\n";
+  for (auto &vec : v) {
+    cout << "  ";
+    printv(vec);
+  }
+  cerr << "]\n";
+}
+void print() { cerr << "\n"; }
+
+template <typename T, typename... TS> void print(T val, TS... vals) {
+  cerr << val << " ";
+  print(vals...);
+}
+
+/* stuff you should look for:
+  ---------------------------
+   * special cases (n=1?)
+   * int overflow, array bounds
+   * do smth instead of nothing and stay organized
+   * WRITE STUFF DOWN
+   * DON'T GET STUCK ON ONE APPROACH
+ */
+
+bool isPalindrome(string &s) { return string(all(s)) == string(rall(s)); }
+
+void solve() {
+  int n;
+  cin >> n;
+  string s;
+  cin >> s;
+  vector<bool> pal(n);
+  if (n & 1)
+    pal[n / 2] = 1;
+  for (int i = 0; i < n / 2; i++) {
+    pal[i] = pal[n - i - 1] = s[i] == s[n - i - 1];
+  }
+  pal.erase(unique(all(pal)), pal.end());
+  n = pal.size();
+  if (count(all(pal), 0) <= 2) {
+    cout << "Yes" << '\n';
+  } else {
+    cout << "No" << '\n';
+  }
+  // string haystack = "";
+  // for (int i = 0; i < n / 2; i++) {
+  //   haystack += (pal[i] ? "R" : "W");
+  // }
+  // if (regex_match(haystack, regex("WR+W"))) {
+  //   cout << "No" << '\n';
+  // } else {
+  //   cout << "Yes" << '\n';
+  // }
+}
+
+int main() {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int tt;
+  cin >> tt;
+  while (tt--) {
+    solve();
+  }
+}
diff --git a/contests/Round#853/B/main_input0.txt b/contests/Round#853/B/main_input0.txt
new file mode 100644
index 0000000..27013f6
--- /dev/null
+++ b/contests/Round#853/B/main_input0.txt
@@ -0,0 +1,7 @@
+3
+4
+1001
+5
+10010
+7
+0111011
diff --git a/contests/Round#853/B/main_input1.txt b/contests/Round#853/B/main_input1.txt
new file mode 100644
index 0000000..a3582ad
--- /dev/null
+++ b/contests/Round#853/B/main_input1.txt
@@ -0,0 +1,3 @@
+1
+6
+100100
\ No newline at end of file
diff --git a/contests/Round#853/B/main_input2.txt b/contests/Round#853/B/main_input2.txt
new file mode 100644
index 0000000..33a4575
--- /dev/null
+++ b/contests/Round#853/B/main_input2.txt
@@ -0,0 +1,3 @@
+1
+6
+011100
\ No newline at end of file
diff --git a/contests/Round#853/B/main_input3.txt b/contests/Round#853/B/main_input3.txt
new file mode 100644
index 0000000..8435e27
--- /dev/null
+++ b/contests/Round#853/B/main_input3.txt
@@ -0,0 +1,3 @@
+1
+7
+0011011
\ No newline at end of file
diff --git a/contests/Round#853/B/main_input4.txt b/contests/Round#853/B/main_input4.txt
new file mode 100644
index 0000000..c64122e
--- /dev/null
+++ b/contests/Round#853/B/main_input4.txt
@@ -0,0 +1,3 @@
+1
+2
+10
\ No newline at end of file
diff --git a/contests/Round#853/B/main_input5.txt b/contests/Round#853/B/main_input5.txt
new file mode 100644
inde