69 lines
2.4 KiB
C++
69 lines
2.4 KiB
C++
// Copyright 2005, Google Inc.
|
|
// All rights reserved.
|
|
//
|
|
// Redistribution and use in source and binary forms, with or without
|
|
// modification, are permitted provided that the following conditions are
|
|
// met:
|
|
//
|
|
// * Redistributions of source code must retain the above copyright
|
|
// notice, this list of conditions and the following disclaimer.
|
|
// * Redistributions in binary form must reproduce the above
|
|
// copyright notice, this list of conditions and the following disclaimer
|
|
// in the documentation and/or other materials provided with the
|
|
// distribution.
|
|
// * Neither the name of Google Inc. nor the names of its
|
|
// contributors may be used to endorse or promote products derived from
|
|
// this software without specific prior written permission.
|
|
//
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
|
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
// A sample program demonstrating using Google C++ testing framework.
|
|
//
|
|
// Author: wan@google.com (Zhanyong Wan)
|
|
|
|
#include "sample1.h"
|
|
|
|
// Returns n! (the factorial of n). For negative n, n! is defined to be 1.
|
|
int Factorial(int n) {
|
|
int result = 1;
|
|
for (int i = 1; i <= n; i++) {
|
|
result *= i;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
// Returns true iff n is a prime number.
|
|
bool IsPrime(int n) {
|
|
// Trivial case 1: small numbers
|
|
if (n <= 1) return false;
|
|
|
|
// Trivial case 2: even numbers
|
|
if (n % 2 == 0) return n == 2;
|
|
|
|
// Now, we have that n is odd and n >= 3.
|
|
|
|
// Try to divide n by every odd number i, starting from 3
|
|
for (int i = 3; ; i += 2) {
|
|
// We only have to try i up to the squre root of n
|
|
if (i > n/i) break;
|
|
|
|
// Now, we have i <= n/i < n.
|
|
// If n is divisible by i, n is not prime.
|
|
if (n % i == 0) return false;
|
|
}
|
|
|
|
// n has no integer factor in the range (1, n), and thus is prime.
|
|
return true;
|
|
}
|