说明下列程序的功能，并给出程序执行结果(6分)。
#include<stdio.h>
#define n 4
int m=0,a[n]；
int ok(int i, int j)
{ intj1,il,okl;
j]=j;i]=i; ok]=1;
while((jl>l)&&ok1) {1--; okI=a[j1]!=i;}
j]=j;i]=i;
while( j1>1)&&(il>1)&&okl) (j1;il; ok1=a[j1]!=i1 ;)
j]=j;i]=i;
while ( (jl>1)&&(i1<n)&&okl) (j1-;il++; okl=a[j1]!=il ;)
return ok];
｝
void unknown2 (int j)
｛ int i;
if(j> n)
｛m++; printf("m= %d ",m);
for(i=l;i<=n;i+) printf(" %d",a[i]);
printf("\n");
else for( i=l; i<=n;i++)
if(ok(i,j)[ a[j]=i; unknown2(j+l);)
｝
main0
｛ unknown2(1);｝ 
