Created
August 3, 2012 19:52
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Mergesort in C!
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#include <stdlib.h> | |
#include <stdio.h> | |
int* merge_sort(int* ,int, int); | |
void merge(int*, int, int, int, int); | |
int main(void) { | |
int *return_array_ptr; | |
int array[] = {2,4,6,5,1,9,7,8,0,3,10, -1, -22, 22}; | |
int len = sizeof(array)/sizeof(int); | |
return_array_ptr = merge_sort(array, 0, len - 1); | |
int i; | |
for (i = 0; i < len; ++i) | |
{ | |
printf("%d,", *(return_array_ptr + i)); | |
} | |
printf("\n"); | |
return 0 ; | |
} | |
int* merge_sort(int* array, int beg, int end) | |
{ | |
if (end - beg == 0) { | |
return array; | |
} | |
else { | |
// split array into two pieces | |
int mid = (end + beg) / 2; | |
merge_sort(array, beg, mid); | |
merge_sort(array, mid + 1, end); | |
merge(array, beg, mid, mid + 1, end); | |
} | |
return array; | |
} | |
void merge(int* array, int l_beg, int l_end, int r_beg, int r_end) { | |
int size = r_end - l_beg + 1; | |
int *new_array = malloc(sizeof(int) * size); | |
int i = 0, j = 0, k; | |
for (k = 0; k < size; k++) | |
{ | |
if (i > l_end - l_beg) { | |
new_array[k] = array[r_beg + j]; | |
printf("%d inserted into array\n", array[r_beg + j]); | |
j++; | |
} | |
else if (j > r_end - r_beg) | |
{ | |
new_array[k] = array[l_beg + i]; | |
printf("%d inserted into array\n", array[l_beg + i]); | |
i++; | |
} | |
else if (array[l_beg + i] < array[r_beg + j]) | |
{ | |
new_array[k] = array[l_beg + i]; | |
printf("%d inserted into array\n", array[l_beg + i]); | |
i++; | |
} | |
else if (array[r_beg + j] < array[l_beg + i]) | |
{ | |
new_array[k] = array[r_beg + j]; | |
printf("%d inserted into array\n", array[r_beg + j]); | |
j++; | |
} | |
} | |
// copy new into old positions | |
int x; | |
for (x = 0; x < size; x++) | |
{ | |
array[l_beg + x] = new_array[x]; | |
} | |
free(new_array); | |
} |
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