[libcxx-commits] [libcxx] [libcxx] adds ranges::fold_left_with_iter and ranges::fold_left (PR #75259)

[via libcxx-commits]

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@@ -0,0 +1,65 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LIBCXX_TEST_MATHS_H
+#define LIBCXX_TEST_MATHS_H
+
+#include <algorithm>
+#include <cassert>
+#include <concepts>
+#include <ranges>
+#include <vector>
+
+template <std::ranges::forward_range R>
+constexpr std::ranges::range_value_t<R> triangular_sum(R& input) {
+  assert(not std::ranges::empty(input));
+  auto [min, max] = std::ranges::minmax_element(input);
+  return static_cast<std::ranges::range_value_t<R>>(
+      (static_cast<double>(std::ranges::distance(input)) / 2) * (*min + *max));
+}
+
+template <std::integral I>
+constexpr I factorial(I const n) {
+  assert(n >= 0);
+  auto result = I(1);
+  for (auto i = I(1); i <= n; ++i) {
+    result *= i;
+  }
+
+  return result;
+}
+static_assert(factorial(0) == 1);
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EricWF wrote:

Cool beans. Love it.

https://github.com/llvm/llvm-project/pull/75259