48.c

#include<stdio.h>
#include<stdlib.h>

voidrotate(int**matrix, intn) {
inti, j, k;
intt;

for (k=0, i=n-1; i >= 0; i-=2, k++) {
for (j=0; j<i; j++) {
/* backup left-up */
t=matrix[k][k+j];
/* left-down to left-up */
matrix[k][k+j] =matrix[i+k-j][k];
/* right-down to left-down */
matrix[i+k-j][k] =matrix[i+k][i+k-j];
/* right-up to right-down */
matrix[i+k][i+k-j] =matrix[k+j][i+k];
/* left-up to right-up */
matrix[k+j][i+k] =t;
 }
 }
}

intmain() {
inti, j, n;
n=5;
int**mat= (int**)calloc(n, sizeof(int*));
for (i=0; i<n; i++) {
mat[i] = (int*)calloc(n, sizeof(int));
 }

for (i=0; i<n; i++) {
for (j=0; j<n; j++) {
mat[i][j] =n*i+j+1;
 }
 }

for (i=0; i<n; i++) {
for (j=0; j<n; j++) {
printf("%2d ", mat[i][j]);
 }
printf("\n");
 }
printf("--------------\n");

rotate(mat, n);

for (i=0; i<n; i++) {
for (j=0; j<n; j++) {
printf("%2d ", mat[i][j]);
 }
printf("\n");
 }
return0;
}