feat(codeforces): 998

codeforces/998/d.cc

@@ -0,0 +1,120 @@
+#include <bits/stdc++.h>
+
+// https://codeforces.com/blog/entry/96344
+
+#pragma GCC optimize("O2,unroll-loops")
+#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
+
+using namespace std;
+
+template <typename... Args>
+void dbg(std::string const &str, Args &&...args) {
+  std::cout << std::vformat(str, std::make_format_args(args...));
+}
+
+template <typename T>
+void dbg(T const &t) {
+  std::cout << t;
+}
+
+template <std::ranges::range T>
+void dbgln(T const &t) {
+  if constexpr (std::is_convertible_v<T, char const *>) {
+    std::cout << t << '\n';
+  } else {
+    for (auto const &e : t) {
+      std::cout << e << ' ';
+    }
+    std::cout << '\n';
+  }
+}
+
+void dbgln() {
+  std::cout << '\n';
+}
+
+template <typename... Args>
+void dbgln(std::string const &str, Args &&...args) {
+  dbg(str, std::forward<Args>(args)...);
+  cout << '\n';
+}
+
+template <typename T>
+void dbgln(T const &t) {
+  dbg(t);
+  cout << '\n';
+}
+
+template <typename T>
+constexpr T MIN = std::numeric_limits<T>::min();
+
+template <typename T>
+constexpr T MAX = std::numeric_limits<T>::max();
+
+template <typename T>
+static T sc(auto &&x) {
+  return static_cast<T>(x);
+}
+
+#define ff first
+#define ss second
+#define eb emplace_back
+#define ll long long
+#define ld long double
+#define vec vector
+#define endl '\n'
+
+#define all(x) (x).begin(), (x).end()
+#define rall(x) (r).rbegin(), (x).rend()
+#define sz(x) static_cast<int>((x).size())
+#define FOR(a, b, c) for (int(a) = (b); (a) < (c); ++(a))
+#define ROF(a, b, c) for (int(a) = (b); (a) > (c); --(a))
+
+static void YES() {
+  std::cout << "YES\n";
+}
+
+static void NO() {
+  std::cout << "NO\n";
+}
+
+vec<int> a;
+
+void solve() {
+  int n;
+  cin >> n;
+  a.resize(n);
+  for (auto &e : a)
+    cin >> e;
+
+  if (a[0] > a[1]) {
+    NO();
+    return;
+  }
+
+  a[1] -= a[0];
+
+  FOR(i, 2, n) {
+    auto x = min(a[i], a[i - 1]);
+    a[i - 1] -= x;
+    a[i] -= x;
+    if (a[i - 1] > a[i]) {
+      NO();
+      return;
+    }
+  }
+  YES();
+}
+
+int main() {
+  cin.tie(nullptr)->sync_with_stdio(false);
+
+  int t = 1;
+  cin >> t;
+
+  while (t--) {
+    solve();
+  }
+
+  return 0;
+}