对长度为 1M 的数组进行排序的数组声明中的可能错误

Question

我需要使用选择排序来排序100K、150K、200K和1M长度的arrays，并显示排序每个数组所需的时间，以及元素与元素比较的数量。

我通过创建一个数组来做到这一点，该数组的元素作为 arrays 的长度。 然后我用所述数组运行了一个 for 循环，并传递了用作要创建的未排序数组的大小的元素，并创建了一个随机生成的数组。

然后我使用 function 调用进行排序。

该程序对于我的前 3 个数组长度（100K、150K 和 200K）运行没有问题，但是对于 1M 数组长度排序它根本没有运行。

我无法弄清楚程序的哪一点停止执行。 我首先认为问题在于我的 integer 声明，因为其中一些声明存储的数量高达一百万。 为此，我定期放置 printf 语句以了解程序流在何处被中断，令人惊讶的是数组声明（这对我来说似乎是这样，但不确定）。

我附上了我得到的代码和 output。

代码：

// C program for implementation of selection sort 
#include <stdio.h> 
#include <time.h>
#include <stdlib.h>

long long int counterS = 0; //counter for number of element to element comparisons


void swap(int *xp, int *yp) //swap function
{ 
    int temp = *xp; 
    *xp = *yp; 
    *yp = temp; 
} 

void selectionSort(int arr[], long long int n) 
{ 
    long long int i, j, min_idx;    //used long long int cuz they reach upto 10^6 order

    // One by one move boundary of unsorted subarray 
    for (i = 0; i < n-1; i++) 
    { 
        // Find the minimum element in unsorted array 
        min_idx = i; 
        for (j = i+1; j < n; j++) {
            if (arr[j] < arr[min_idx]) 
                min_idx = j; 
            ++counterS;             //increments each time a comparison occurs
        }
        // Swap the found minimum element with the first element 
        swap(&arr[min_idx], &arr[i]); 
    } 
} 


// Driver program to test above functions 
int main() 
{ 
    clock_t tic1, toc1;
    int sz[4]={100000,150000, 200000, 1000000}; //array having array lengths  
    int k;

    for(k=0;k<4;k++){
    printf("1st check: It's the long long int declaration\n");  //1st check to get to know where it went wrong
    long long int size = sz[k];
    printf("2nd check: It's the array declaration\n");          //2nd check to know where it went wrong
    int arr[size];
    printf("3rd check: It's not the array declaration\n");      //3rd check to know where it went wrong

    long long int i;
    for(i=0;i<size;i++)
        arr[i]=rand()%100;

    long long int n = sizeof(arr)/sizeof(arr[0]); 
    printf("4th check: It's the random array generation\n");    //4th check to know where it went wrong

    tic1 = clock();
    selectionSort(arr, n); 
    toc1 = clock();
    double time_taken = (double)(toc1-tic1)/CLOCKS_PER_SEC;
    printf("5th check: It's the function call\n");              //5th check to know where it went wrong

    printf("Selection Sort - time = %lf seconds, element by element comparisons = %lld\n",
    time_taken, counterS );
    }
    return 0; 
} 

Output：

1st check: It's the long long int declaration
2nd check: It's the array declaration
3rd check: It's not the array declaration
4th check: It's the random array generation
5th check: It's the function call
Selection Sort - time = 11.458000 seconds, element by element comparisons = 4999950000
1st check: It's the long long int declaration
2nd check: It's the array declaration
3rd check: It's not the array declaration
4th check: It's the random array generation
5th check: It's the function call
Selection Sort - time = 59.196000 seconds, element by element comparisons = 16249875000
1st check: It's the long long int declaration
2nd check: It's the array declaration
3rd check: It's not the array declaration
4th check: It's the random array generation
5th check: It's the function call
Selection Sort - time = 120.349000 seconds, element by element comparisons = 36249775000
1st check: It's the long long int declaration
2nd check: It's the array declaration

Answer 1

在任何 function 之外定义您的大型阵列。

int large[1000000];
int main(void) {
    int sz[4] = {100000, 150000, 200000, 1000000};
    for (int k = 0; k < 4; k++) {
        // use the first sz[k] elements of large
    }
}

Answer 2

由于其他一切都在工作，我会说您没有足够的位在 go 上分配 1M 大小的连续数组，因此正如其他人评论的那样，我建议malloc() 。 class 中的其他人可能有这个工作，因为在他们的机器上有足够的堆栈空间在 go 上分配 1M。 看看malloc()是否解决了它，然后您就确定了。