合并排序中的cout分段错误

Question

我读了很多文章，但我不知道我的错误在哪里，所以我就这么做了。我的程序在cout<<endl上抛出segfault。当我擦除它时，程序甚至不会打印任何内容。它只是打印segfault。很显然，程序从未达到对向量进行排序的目的。

#include <iostream>
#include <vector>
using namesapce std
void inserctionSort(std::vector<double> &v, int i, int j)
{
double temp;
for(i; i < v.size(); i++)
{
temp = v[i];
j = i - 1;
while((v[j] > temp) && (j >= 0))
{
v[j+1] = v[j];
j--;
}
v[j+1] = temp;
}
}
void merge_(std::vector<double> &v, int i, int k, int j)
{
std::vector<double> w(v.size());
int n = j - i + 1;
int p = i;
int q = k + 1;
for(int l = 0; l < n; l++)
{
if(p <= k && (q > j || v[p] <= v[q]))
{
w[l] = v[p];
p++;
}else
{
w[l] = v[q];
q++;
}
}
for(int l = 0; l < n; l++)
v[i - 1 + l] = w[l];
}
void mergeSort(std::vector<double> &v, int i, int j)
{
int n = j - i + 1, n0 = 3;
int k;
if(n <= n0)
{
inserctionSort(v,i,j);
}else
{
k = i - 1 + n / 2;
mergeSort(v, i, k);
mergeSort(v, k + 1, j);
merge_(v, i, k, j);
}
}
int main()
{
vector<double> v1 = {3.2,4.1,55.42,2.24,5.424,667.32,35.54};
cout<<"Vector desordenado: ";
for(int i = 0; i < v1.size(); i++)
cout<<v1[i]<<", ";
cout<<"hola";
cout<<endl;
cout<<"hola";
mergeSort(v1, 0, v1.size()-1); //--> Core generado
//quickSort(v1, 0, v1.size()-1);
cout<<"Vector ordenado: ";
for(int i = 0; i < v1.size(); i++)
cout<<v1[i]<<", ";
return 0;
}

Answer 1

您的代码中存在向量索引在几个循环中假定值为-1的问题。我已经纠正了以下错误，你的代码的工作版本：

#include <iostream>
#include <vector>
using namespace std;
void inserctionSort(vector<double> &v, int i, int j)
{
int v_size = v.size();
double temp;
for (; i < v_size; i++) {
temp = v[i];
j = i - 1;
while ( (j >= 0) && (v[j] > temp) ) {  // swapped conditions, as when j=-1, v[j]>temp is undefined
v[j+1] = v[j];
j--;
}
v[j+1] = temp;
}
}
void merge_(vector<double> &v, int i, int k, int j)
{
vector<double> w( v.size() );
int n = j - i + 1;
int p = i;
int q = k + 1;
for (int l = 0; l < n; l++) {
if ( p <= k && (q > j || v[p] <= v[q]) ) {
w[l] = v[p];
p++;
} else {
w[l] = v[q];
q++;
}
}
for(int l = 0; l < n; l++)      
v[i + l] = w[l];          // deleted -1 from v[i - 1 + l], as it leads to v[-1] for i,l = 0
}
void mergeSort(vector<double> &v, int i, int j)
{
int n = j - i + 1, n0 = 3;  // n = v.size()
int k;
if (n <= n0) {
inserctionSort(v,i,j);
} else {
k = i - 1 + n / 2;
mergeSort(v, i, k);
mergeSort(v, k + 1, j);
merge_(v, i, k, j);
}
}
int main()
{
vector<double> v1 = {3.2,4.1,55.42,2.24,5.424,667.32,35.54};
cout<<"Vector desordenado: ";
for (unsigned i = 0; i < v1.size(); i++)
cout<<v1[i]<<", ";
cout << "hola";
cout << endl;
cout << "hola";
mergeSort(v1, 0, v1.size()-1); //--> Core generado
//quickSort(v1, 0, v1.size()-1);
cout<<"Vector ordenado: ";
for (unsigned  i = 0; i < v1.size(); i++)
cout << v1[i] << ", ";
return 0;
}