翻硬币问题

#include <iostream>
#include <cstring>
using namespace std;
const int MAXN = 1<<7;
bool b[MAXN];
int a[7];
void toarr(int x) {
for (int i = 0; i < 7; i++) {
a[i] = x % 2;
x /= 2;
}
}
int to2()
{
int x = 0;
for (int i = 0; i < 7; i++) {
x += (a[i] << i);
}
return x;
}
void print()
{
for (int i = 0; i < 7; i++) {
cout << a[i];
}
cout << endl;
}
void dfs(int x) {
print();
for (int i = 0; i < 7; i++) {
for (int j = 0; j < i; j++) {
a[i] = 1 - a[i];
a[j] = 1 - a[j];
int t = to2();
if (!b[t]) {
b[t] = true;
dfs(to2());
}
a[i] = 1 - a[i];
a[j] = 1 - a[j];
}
}
}
int main()
{
memset(b, 0, sizeof(b));
b[0] = true;
dfs(0);
}