全排列

#include<iostream>
using namespace std;
int A[5] = {1,2,3,4,5};
int B[5];
void permutation(int n,int curr)
{
if (curr == n)
{
for (int i = 0; i < n; i++)
cout << B[i] << " ";
cout << endl;
return;
}
else
{
for (int j = 0; j < n; j++)
{
bool flag = true;
//设置B[curr]为A[j]
B[curr] = A[j];
//B[curr]不在集合中时，继续下一次递归
for (int i = 0; i < curr; i++)
{
if (B[curr] == B[i])
{
flag = false;
break;
}
}
if (flag)
{
permutation(n, curr + 1);
}
}
}
}
int main()
{
permutation(5,0);
return 0;
}

#include<iostream>
#include<algorithm>
using namespace std;
int A[8];//目标集合
int B[8];//候选集合
void permutation(int n,int curr)
{
if (curr == n)
{
for (int i = 0; i < n-1; i++)
cout << B[i] << " ";
cout << B[n-1];
cout << endl;
return;
}
else
{
for (int j = 0; j < n; j++)
{
if (!j || A[j] != A[j - 1])
{
B[curr] = A[j];
int c1 = 0;//目标集合中包含B[curr]的次数
int c2 = 0;//候选集合中包含B[curr]的次数
for (int i = 0; i < curr; i++)
{
if (B[i] == A[j])
{
c1++;
}
}
for (int i = 0; i < n; i++)
{
if (A[i] == A[j])
{
c2++;
}
}
if (c1 < c2)
{
permutation(n, curr + 1);
}
}

}
}
}
int comp(const void*a, const void*b)
{
return *(int*)a - *(int*)b;
}
int main()
{
int N;
cin >> N;
for (int i = 0; i < N; i++)
cin >> A[i];
qsort(A, N, sizeof(int),comp);
permutation(N,0);
return 0;
}