字典序法生成全排列

/*用字典序法生成全排列*/#include<stdio.h>#include<stdlib.h>void generate_i(int *p,int n,int *i){int j=n;while(p[j-1]>=p[j]){j--;}*i=j;}void generate_j(int *p,int n,int i,int *j){int k=n;while(p[i-1]>=p[k]){k--;}*j=k;}void swap(int *a,int *b){*a=(*a)^(*b);*b=(*a)^(*b);*a=(*a)^(*b);}void reverse(int *p,int i,int n){int k;for(k=0;k<(n-i+1)/2;k++){swap(&p[k+i],&p[n-k]);}}void print(int *p,int n){int i;printf("p ");for(i=1;i<=n;i++){printf("%d ",p[i]);}printf("\n\n");}void main(){int n,N,x,i,j,*p;printf("请输入n:");scanf("%d",&n);p=(int*)malloc((n+1)*sizeof(n));for(x=1;x<=n;x++){p[x]=x;}print(p,n);//求n的阶乘得Nfor(x=n,N=1;x>1;x--){N*=x;}for(x=0;x<N-1;x++){generate_i(p,n,&i);generate_j(p,n,i,&j);swap(&p[i-1],&p[j]);reverse(p,i,n);print(p,n);}free(p);scanf("%d",&n);}