Project Euler problem 43

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <stack>
#include <cmath>
#include <map>
#include <ctime>
#define MAXN 1111111
#define MAXM 400005
#define INF 2000000007
#define PI acos(-1.0)
using namespace std;
int b[7] = {2, 3, 5, 7, 11, 13, 17};
long long sum = 0;
void dfs(long long num, int bitmask, int deep)
{
if(bitmask == 1023)
{
sum += num;
return;
}
for(int i = 0; i < 10; i++)
if((bitmask & (1 << i)) == 0)
{
int f = (num % 100) * 10 + i;
if(f % b[deep + 1] == 0)
dfs(num * 10 + i, bitmask | (1 << i), deep + 1);
}
}
int main()
{
for(int i = 0; i < 10; i++)
for(int j = 0; j < 10; j++)
for(int k = 0; k < 10; k++)
if(i != j && i != k && j != k)
{
int f = i * 100 + j * 10 + k;
dfs(f, (1 << i) + (1 << j) + (1 << k), -1);
}

return 0;
}