Algorithm (c): merge sort

Merge sort is the same as division method, but different from quick sort

Fast sorting is more biased, and the data exchange between the two sides in the recursive process

The merge sort is more in favor of merging, in order in the recursion of two halves merging

Code:

[email protected]:/mnt/shared/appbox/mgsort# cat mgsort.c#include <stdlib.h> #include <stdlib.h># Include <string.h> #include <unistd.h> #include <stdio.h>static int compare_int (const void *int1,        const void *int2) {if (* (const int *) Int1 = = * (const int *) INT2) return 0; return * (const int *) INT1 > * (const int *) Int2? 1:-1;} static int merge (void *data, int esize, int i, int j, int k, int (*compare) (const void *key1, const void *key2)) {C        Har *a = data;        Char *m;        int IPOs, JPOs, MPOs;        IPOs = i;        JPOs = j + 1;        MPOs = 0;        if ((M = (char *) malloc (Esize * ((k-i) +1)) = = NULL) return-1;                while (IPOs <= J | | JPOs <= k) {if (IPOs > J)//left no further elements to merge {while (JPOs <= k)//merge right {memcpy (&m[mpos * Esize], &a[jpos *Esize], esize);                                jpos++;                        mpos++;                } continue; } else if (JPOs > K)//right No more elements to merge {while (IPOs <= j)//merge left {memcpy (&m[mpos * esize], &a[ipos * E                                Size], esize);                                ipos++;                        mpos++;                } continue; //both left and right need merge if (compare (&a[ipos * Esize], &a[jpos * esize]) &L T                                0) {memcpy (&m[mpos * esize], &a[ipos * esize], esize);                                ipos++;                mpos++; } else {memcpy (&m[mpos * esizE], &a[jpos * esize], esize);                                jpos++;                mpos++;        }} memcpy (&a[i * esize], M, Esize * ((k-i) +1));        Free (m); return 0;}  int Mgsort (void *data, int size, int esize, int i, int k, int (*compare) (const void *key1, const void *key2)) {int        J                if (I < k) {j = (int) (((i + k-1))/2);                if (mgsort (data, size, esize, I, J, compare) < 0) return-1;                if (mgsort (data, size, esize, j+1, K, Compare) < 0) return-1;        if (merge (data, Esize, I, J, K, Compare) < 0) return-1; } return 0;}        int main (int argc, char *argv[]) {int ret;        int I, j, K;        i = 11;        j = 12;        int array[10]= {1,4,7,2,5,8,3,6,9,10};        printf ("\n******************compare_init test**********************\n"); printf ("Compare_iNT (&i, &j) =%d\n ", Compare_int (&i, &j));        printf ("Compare_int (&j, &i) =%d\n", Compare_int (&j, &i));        printf ("Compare_int (&i, &i) =%d\n", Compare_int (&i, &i));        printf ("\n******************partition test**********************\n");        Mgsort (array, ten, sizeof (int), 0, 9, compare_int);        for (i=0; i<10; i++) printf ("%d", array[i]);        printf ("\ n"); return 0;}

Operation Result:

[Email protected]:/mnt/shared/appbox/mgsort#./mgsort ******************compare_init test********************** Compare_int (&i, &j) =-1compare_int (&j, &i) =1compare_int (&i, &i) =0****************** Partition    

Algorithm (c): merge sort