我正在编写计数排序功能,当我运行它时会弹出一个窗口,说“filename.exe已停止工作”。经过调试后,它似乎陷入了第二个for
循环。让我感到困惑的是,如果我将maxInt
设置为任何大于130000的数字,那么它可以工作,但如果它的130000或低于我得到的错误信息。我用来排序的文件只有大约20个数字。
#include <iterator>
#include <algorithm>
#include <vector>
#include <fstream>
#include <iostream>
using namespace std;
std::string file = "";
std::vector<int> numbers;
void CountingSort(vector<int> &numbers);
int main()
{
std::cout << "Which file would you like to sort?\n";
std::cin >> file;
std::ifstream in(file.c_str());
// Read all the ints from in:
std::copy(std::istream_iterator<int>(in), std::istream_iterator<int>(),
std::back_inserter(numbers));
CountingSort(numbers);
// Print the vector with tab separators:
std::copy(numbers.begin(), numbers.end(),
std::ostream_iterator<int>(std::cout, "\t"));
std::cout << std::endl;
return 0;
}
struct CalcMaxInt
{
int maxInt;
CalcMaxInt () : maxInt(0) {}
void operator () (int i) { if (i > maxInt) maxInt = i; }
};
void CountingSort(vector<int>& numbers)
{
CalcMaxInt cmi = std::for_each(numbers.begin(), numbers.end(), CalcMaxInt());
//int maxInt = cmi.maxInt + 1;
int maxInt = 130001;
vector <int> temp1(maxInt);
vector <int> temp2(maxInt);
for (int i = 0; i < numbers.size(); i++)
{
temp2[numbers[i]] = temp2[numbers[i]] + 1;
}
for (int i = 1; i <= maxInt; i++)
{
temp2[i] = temp2[i] + temp2[i - 1];
}
for (int i = numbers.size() - 1; i >= 0; i--)
{
temp1[temp2[numbers[i]] - 1] = numbers[i];
temp2[numbers[i]] = temp2[numbers[i]] -1;
}
for (int i =0;i<numbers.size();i++)
{
numbers[i]=temp1[i];
}
return;
}
答案 0 :(得分:2)
您正在尝试访问超出适当范围的元素。 temp2的范围为[0 ... maxInt-1],但以下代码使用的temp2 [maxInt]超出范围。
for (int i = 1; i <= maxInt; i++)
{
temp2[i] = temp2[i] + temp2[i - 1];
}
你必须修复temp2才能拥有maxInt + 1个元素或者i&lt; maxInt不要看错误。
答案 1 :(得分:1)
这不是你这样做的全部要点:
CalcMaxInt cmi = std::for_each(numbers.begin(), numbers.end(), CalcMaxInt());
获取最大元素?
我将您的代码更改为以下内容。
void CountingSort(vector<int>& numbers)
{
CalcMaxInt cmi;
std::for_each(numbers.begin(), numbers.end(), cmi);
int maxInt = cmi.maxInt;
vector <int> temp1(maxInt);
vector <int> temp2(maxInt);
// then the rest the same starting with the for loops
// but with the fix that @kcm1700 mentioned to the for loop
}
答案 2 :(得分:0)
不应该temp1
标注numbers.size()+1
?