C++中涉及新函数和删除[]函数的奇怪错误

我正在做Coursera算法的第一个编程作业：设计和分析课程（https://www.coursera.org/course/algo）。它涉及使用合并排序来计算反转（http://en.wikipedia.org/wiki/Inversion_（discrete_mathematics））。我认为这将是一个相对不费吹灰之力的事情，因为我以前（在学校）遇到过合并排序。

#include <iostream>
#include <fstream>
using namespace std;
int *half(int *array, int n, int start, int end)
{
    /*
     * Creates a new array which contains elements from ''array'' starting with ''start''
     * and ending with ''end - 1''.
     */
     int *new_array = new int[end-start];
     for(int i = start; i < end; i++)
     {
        new_array[i-start] = array[i];
     }
     return new_array;
}
int merge(int *array1, int n1, int *array2, int n2, int *new_array)
{
    /*
     *  Merges arrays 1 and 2 (with lengths n1 and n2) into a new_array, counting
     *  ''split inversions'' by the way.
     */
    int i = 0, j = 0, count = 0;
    for(int k = 0; k < n1 + n2; k++)
    {
         if(i >= n1)
        {
            new_array[k] = array2[j];
            j++;
            continue;
        }
         if(j >= n2)
        {
            new_array[k] = array1[i];
            i++;
            continue;
        }
        if( array1[i] <= array2[j] )
        {
            new_array[k] = array1[i];
            i++;
        }
        else
        {
            new_array[k] = array2[j];
            j++;
            count++;
        }
    }
    return count;
}
int mergesort(int *array, int n)
{
    if(n == 1) return 0; //base case
    int x, y, z;
    int odd;
    if(n%2 == 0) odd = 0;
    else odd = 1;
    int *half1 = new int [n/2];
    int *half2 = new int [n/2 + odd];
    half1 = half(array, n, 0, n/2);
    half2 = half(array, n, n/2, n);
    x = mergesort(half1, n/2);
    y = mergesort(half2, n/2 + odd);  //if n is odd, we add one
    z = merge(half1, n/2, half2, n/2 + odd, array); //we write a sorted array back in our starting array
    delete [] half1;
    delete [] half2;
    return x + y + z;
}
int main()
{
    int n;
    int *array = new int[n];
    cin >> n;
    for(int i = 0; i < n; i++)
    {
        int x;
        cin >> x;
        array[i] = x;
    }
    for(int i = 0; i < n; i++)
        cout << array[i] << " ";
    cout << endl;
    cout << "Number of inversions: " << mergesort(array, n) << endl;
    for(int i = 0; i < n; i++)
    cout << array[i] << " ";
    cout << endl;
    delete[] array;
    return 0;
}

那么，这里有什么奇怪的呢？第一件事：对我来说，它适用于某些数组，但对于其他数组会崩溃（稍后的示例）。第二件事：我把代码发给我的朋友，他说对他来说一切都很好，即使是对我来说急剧崩溃的例子。

所以，例子：

对于数组 [1 2 3 4 5 6 7] g++ 生成以下内容：

malloc.c:2451: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed.
Aborted (core dumped)

当我使用 gdb"回溯"它时：

#0  0x00007ffff7753445 in __GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#1  0x00007ffff7756bab in __GI_abort () at abort.c:91
#2  0x00007ffff779abed in __malloc_assert (assertion=<optimized out>, file=<optimized out>, line=<optimized out>, function=<optimized out>) at malloc.c:300
#3  0x00007ffff779e0f4 in sYSMALLOc (av=0x7ffff7ad3720, nb=32) at malloc.c:2448
#4  _int_malloc (av=0x7ffff7ad3720, bytes=12) at malloc.c:3892
#5  0x00007ffff779fa45 in __GI___libc_malloc (bytes=12) at malloc.c:2924
#6  0x00007ffff7b8fded in operator new(unsigned long) () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#7  0x00007ffff7b8ff09 in operator new[](unsigned long) () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#8  0x0000000000400b12 in mergesort (array=0x603010, n=7) at jedan.cpp:81
#9  0x0000000000400cfe in main () at jedan.cpp:120

它对数组 [1 2 3 4 5 6 7 8 9 10] 执行类似操作（但不相同！），再次连接到 new 和 delete[] 函数。如果有人认为这会有所帮助，我可以稍后在这里发布，但我不想过多地膨胀这篇文章。它适用于我尝试过的大多数数组（我对大小为 <= 6 的数组以及大量较大的数组都没有问题）。

我正在使用昨天安装的 Ubuntu 12.04...相当干净清新。帮助？

附言如果您发现变量名称有点奇怪，对不起...我从我的母语翻译了它们，这样代码就可以更具可读性。