Solved A from the last Div2

1 files changed, 143 insertions, 0 deletions

diff --git a/contests/Round889/A/main.cpp b/contests/Round889/A/main.cpp
new file mode 100755
index 0000000..7db0097
--- /dev/null
+++ b/contests/Round889/A/main.cpp
@@ -0,0 +1,143 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+using ll = long long;
+using pii = pair<int, int>;
+using vpi = vector<pii>;
+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
+#define make_unique(x)                                                         \
+  sort(all((x)));                                                              \
+  (x).resize(unique(all((x))) - (x).begin())
+#define ceil(a, b) ((a) + (b) - 1) / (b))
+
+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};
+
+template <typename K, typename V>
+ostream &operator<<(ostream &os, const pair<K, V> &p);
+template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec);
+template <typename K, typename V>
+ostream &operator<<(ostream &os, const map<K, V> &m);
+template <typename K, typename V>
+ostream &operator<<(ostream &os, const unordered_map<K, V> &m);
+template <typename T> ostream &operator<<(ostream &os, const set<T> &s);
+template <typename T>
+ostream &operator<<(ostream &os, const unordered_set<T> &s);
+
+template <typename K, typename V>
+ostream &operator<<(ostream &os, const pair<K, V> &p) {
+  os << "(" << p.first << ", " << p.second << ")";
+  return os;
+}
+
+template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
+  os << "{";
+  for (size_t i = 0; i < vec.size(); ++i) {
+    if (i > 0)
+      os << ", ";
+    os << vec[i];
+  }
+  os << "}";
+  return os;
+}
+
+template <typename K, typename V>
+ostream &operator<<(ostream &os, const map<K, V> &m) {
+  os << "{";
+  for (const auto &p : m) {
+    os << p.first << ": " << p.second << ", ";
+  }
+  os << "}";
+  return os;
+}
+
+template <typename K, typename V>
+ostream &operator<<(ostream &os, const unordered_map<K, V> &m) {
+  os << "{";
+  for (const auto &p : m) {
+    os << p.first << ": " << p.second << ", ";
+  }
+  os << "}";
+  return os;
+}
+
+template <typename T> ostream &operator<<(ostream &os, const set<T> &s) {
+  int i = 0;
+  os << "{";
+  for (const auto &e : s) {
+    if (i > 0)
+      os << ", ";
+    os << e;
+    i++;
+  }
+  os << "}";
+  return os;
+}
+
+template <typename T>
+ostream &operator<<(ostream &os, const unordered_set<T> &s) {
+  int i = 0;
+  os << "{";
+  for (const auto &e : s) {
+    if (i > 0)
+      os << ", ";
+    os << e;
+    i++;
+  }
+  os << "}";
+  return os;
+}
+
+void dbg() { cerr << "\n"; }
+
+template <typename T, typename... TS> void dbg(T val, TS... vals) {
+  cerr << val << " ";
+  dbg(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
+ */
+
+void solve() {
+  int n;
+  cin >> n;
+  vi v(n);
+  int outOfPlace = 0;
+  for (int i = 0; i < n; i++) {
+    cin >> v[i];
+    outOfPlace += (v[i] == i + 1);
+  }
+  if (outOfPlace % 2 == 0) {
+    cout << outOfPlace / 2 << '\n';
+  } else {
+    cout << (outOfPlace / 2) + 1 << '\n';
+  }
+}
+
+int main() {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int tt;
+  cin >> tt;
+  while (tt--) {
+    solve();
+  }
+}