生成可重集的排列

#include <iostream>
#include <algorithm>
using namespace std;

int n, a[1010], p[1010];
bool cmp(int a, int b){
return a < b;
}
void print_permutation(int cur){   //cur 表示当前确定的元素位置;
if(cur == n){
for(int i = 0; i < n-1; ++i){
cout << a[i] << ' ';
}
cout << a[n-1] << endl;
}
else{
for(int i = 0; i < n; ++i){
if(!i || p[i] != p[i-1]){  //枚举的i应该不重复，不遗漏的取遍所有的p[i]值;
int c1 = 0, c2 = 0;
for(int j = 0; j < n; ++j){
if(p[j] == p[i])  //p数组中p[i]出现的次数;
++c1;
}
for(int j = 0; j < cur; ++j){
if(a[j] == p[i])  //a数组中p[i]目前出现的次数;
++c2;
}
if(c2 < c1){
a[cur] = p[i];
print_permutation(cur+1);
}
}
}
}
}
int main()
{
int count(0), a;
while(cin >> a){
p[count++] = a;
}
n = count;
sort(p, p+n, cmp);
print_permutation(0);
}