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codeforces/19/.clang-format

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+BasedOnStyle: Google
+IndentWidth: 2
+ColumnLimit: 100
+PointerAlignment: Left

codeforces/19/19txt

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+A. Alternating Sum of Numbers
+time limit per test
+2 seconds
+memory limit per test
+256 megabytes
+input
+standard input
+output
+standard output
+You are given a sequence of integers. Output the alternating sum of this sequence. In other words, output a1−a2+a3−a4+a5−…
+a
+1
+−
+a
+2
++
+a
+3
+−
+a
+4
++
+a
+5
+−
+…
+. That is, the signs of plus and minus alternate, starting with a plus.
+
+Input
+The first line of the test contains one integer t
+t
+ (1≤t≤1000
+1
+≤
+t
+≤
+1000
+) — the number of test cases. Then follow t
+t
+ test cases.
+
+The first line of each test case contains one integer n
+n
+ (1≤n≤50
+1
+≤
+n
+≤
+50
+) — the length of the sequence. The second line of the test case contains n
+n
+ integers a1,a2,…,an
+a
+1
+,
+a
+2
+,
+…
+,
+a
+n
+ (1≤ai≤100
+1
+≤
+a
+i
+≤
+100
+).
+
+Output
+Output t
+t
+ lines. For each test case, output the required alternating sum of the numbers.
+
+Example
+Input
+Copy
+4
+4
+1 2 3 17
+1
+100
+2
+100 100
+5
+3 1 4 1 5
+Output
+Copy
+-15
+100
+0
+10

codeforces/19/2010a.cc

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+#include <bits/stdc++.h>  // {{{
+
+#include <version>
+#ifdef __cpp_lib_ranges_enumerate
+#include <ranges>
+namespace rv = std::views;
+namespace rs = std::ranges;
+#endif
+
+#pragma GCC optimize("O2,unroll-loops")
+#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
+
+using namespace std;
+
+using i16 = int16_t;
+using u16 = uint16_t;
+using i32 = int32_t;
+using u32 = uint32_t;
+using i64 = int64_t;
+using u64 = uint64_t;
+using f64 = double;
+using f128 = long double;
+
+#if __cplusplus >= 202002L
+template <typename T>
+constexpr T MIN = std::numeric_limits<T>::min();
+
+template <typename T>
+constexpr T MAX = std::numeric_limits<T>::max();
+#endif
+
+#ifdef LOCAL
+#define db(...) std::print(__VA_ARGS__)
+#define dbln(...) std::println(__VA_ARGS__)
+#else
+#define db(...)
+#define dbln(...)
+#endif
+//  }}}
+
+void solve() {
+  u32 n;
+  cin >> n;
+  i32 ans = 0;
+  i32 a;
+  for (u32 i = 0; i < n; ++i) {
+    cin >> a;
+    ans += a * ((i & 1) ? -1 : 1);
+  }
+  println("{}", ans);
+}
+
+int main() {  // {{{
+  std::cin.exceptions(std::cin.failbit);
+#ifdef LOCAL
+  std::cerr.rdbuf(std::cout.rdbuf());
+  std::cout.setf(std::ios::unitbuf);
+  std::cerr.setf(std::ios::unitbuf);
+#else
+  std::cin.tie(nullptr)->sync_with_stdio(false);
+#endif
+  u32 tc = 1;
+  std::cin >> tc;
+  for (u32 t = 0; t < tc; ++t) {
+    solve();
+  }
+  return 0;
+}
+// }}}

codeforces/19/io/2010a.1.cpin

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+4
+4
+1 2 3 17
+1
+100
+2
+100 100
+5
+3 1 4 1 5

codeforces/19/io/2010a.1.cpout

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+-15
+100
+0
+10

codeforces/19/io/2010b.1.cpin

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+3 1

codeforces/19/io/2010b.1.cpout

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+2

codeforces/19/io/2010c1.1.cpin

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+abrakadabrabrakadabra

codeforces/19/io/2010c1.1.cpout

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+YES
+abrakadabra

codeforces/19/io/2010c1.2.cpin

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+acacacaca

codeforces/19/io/2010c1.2.cpout

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+YES
+acaca

codeforces/19/io/2010c1.3.cpin

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+abcabc

codeforces/19/io/2010c1.3.cpout

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+NO

codeforces/19/io/2010c1.4.cpin

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+abababab

codeforces/19/io/2010c1.4.cpout

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+YES
+ababab

codeforces/19/io/2010c1.5.cpin

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+tatbt

codeforces/19/io/2010c1.5.cpout

@@ -0,0 +1 @@
+NO

codeforces/19/io/2010c2.1.cpin

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+abrakadabrabrakadabra

codeforces/19/io/2010c2.1.cpout

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+YES
+abrakadabra

codeforces/19/io/2010c2.2.cpin

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+acacacaca

codeforces/19/io/2010c2.2.cpout

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+YES
+acacaca

codeforces/19/io/2010c2.3.cpin

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+abcabc

codeforces/19/io/2010c2.3.cpout

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+NO

codeforces/19/io/2010c2.4.cpin

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+abababab

codeforces/19/io/2010c2.4.cpout

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+YES
+ababab

codeforces/19/io/2010c2.5.cpin

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+tatbt

codeforces/19/io/2010c2.5.cpout

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+NO