# 在C中调试合并排序实现

``````#include <stdio.h>
#include <limits.h>
#include <math.h>

void merge(int *A,float p,float q,float r)
{
float n = r - p + 1; /* number of elements in array A */
int n1 = (int) (q - p + 1);
int n2 = (int) (r - q);
printf("n2 = %d\n",n2);
int  i, j;
float k;

int *L, *R;
for (i = 1; i <= n1; i++){
L[i] = A[(int) (p + i - 1)];
}

for (j = 1; j < n2; j++){
R[j] = A[(int) (q + j)];
}

L[n1+1] = INT_MAX;
R[n2+1] = INT_MAX;

i = 1;
j = 1;

printf("p = %f\n",p);
printf("r = %f\n",r);

for (k = p; k <= r; k++){
printf("k=%f\n",k);
if (L[i] <= R[j]){
A[(int) k] = L[i];
i += 1;
}

else{
A[(int) k] = R[j];
j += 1;
}
}
}

void merge_sort(int *A, float p, float r)
{
int i;
/*  for (i=0; i<=r-p;i++){
printf("%d\n",A[i]);
}*/
float q;
if (p < r){
/*  printf("merge_sort p = %d\n",p);
printf("merge_sort r = %d\n",r);*/
q = floor((p + r)/2);
/*      printf("q = %f\n",q);*/
merge_sort(A, p, q);
merge_sort(A, q+1, r);
/*      printf("done\n");*/
merge(A, p, q, r);
}
}

int main()
{
int x, c, *array;
int n;

printf("Enter number of elements\n");
scanf("%d",&n);

printf("Enter %d elements\n",n);

for (c = 0; c < n; c++){
scanf("%d", &array[c]);
}

merge_sort(array, 0, n-1);

for (c = 0; c < n; c++){
printf("%d\n", array[c]);
}
}
``````

``````int *L, *R;
for (i = 1; i <= n1; i++){
L[i] = A[(int) (p + i - 1)];
}
``````

`L`并且`R`未初始化使用

``````   int x, c, *array;

...

for (c = 0; c < n; c++){
scanf("%d", &array[c]);
``````

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