#include <iostream>
#include <vector>
#include <assert.h>
using namespace std;
void PermRecur(vector<int>& num, vector<int>& use, vector<int>& res, int k)
{
//如果下标k等于size，说明所有元素已经放置完毕
if (k == res.size())
{
for (int i = 0; i < k; ++i)
cout << res[i] << ' ';
cout << endl;
return;
}
for (int i = 0; i < num.size(); ++i)
{
//标记大于0说明还有剩余的元素没有放置
if (use[i] > 0)
{
//元素被放置后次数减1
--use[i];
res[k] = num[i];
PermRecur(num, use, res, k + 1);
//递归结束后再将该元素的次数加1
++use[i];
}
}
}
void Perm(vector<int>& ivec)
{
assert(!ivec.empty());
int size=ivec.size();
vector<int> res(size);
vector<int> use;
vector<int> num;
use.push_back(1);
num.push_back(ivec[0]);
for(int i=1; i<size; ++i)
{
int j=0;
for(; j<num.size();++j)
{
if(ivec[i]==num[j])
{
++use[j];
break;
}
}
if(j==num.size())
{
use.push_back(1);
num.push_back(ivec[i]);
}
}
cout<<"num: ";
for(int i=0; i<num.size(); i++)
{
cout<<num[i]<<" ";
}
cout<<endl;
cout<<"use: ";
for(int i=0; i<use.size(); i++)
{
cout<<use[i]<<" ";
}
cout<<endl;
PermRecur(num, use, res, 0);
}
int main()
{
int a[] = {1, 2, 2,3,3,4};
vector<int> ivec(a, a + sizeof(a)/sizeof(a[0]));
cout<<"array: ";
for(int i=0; i<ivec.size(); i++)
{
cout<<ivec[i]<<" ";
}
cout<<endl;
Perm(ivec);
return 0;
}
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