递推DP URAL 1081 Binary Lexicographic Sequence

#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <string>
using namespace std;

const int MAXN = 1e4 + 10;
const int INF = 0x3f3f3f3f;
int dp[50][2];

void solve(void)
{
memset (dp, 0, sizeof (dp));
dp[1][1] = 1;    dp[1][0] = 1;
for (int i=2; i<44; ++i)
{
dp[i][1] = dp[i-1][0];
dp[i][0] = dp[i-1][1] + dp[i-1][0];
}
}

int main(void)        //URAL 1081 Binary Lexicographic Sequence
{
//freopen ("Q.in", "r", stdin);

solve ();
int n, k;
while (scanf ("%d%d", &n, &k) == 2)
{
if (k > dp
[1] + dp
[0])    {puts ("-1");    continue;}
while (n)
{
if (dp
[0] >= k)
{
printf ("0");
}
else    {printf ("1");    k -= dp
[0];}
n--;
}
puts ("");
}

return 0;
}