题目：http://community.topcoder.com/stat?c=problem_statement&pm=13042&rd=15845
参考：http://apps.topcoder.com/wiki/display/tc/SRM+612
典型的dp，将问题划分为相同的子问题。
代码：
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <iostream>
#include <sstream>
#include <iomanip>
#include <bitset>
#include <string>
#include <vector>
#include <stack>
#include <deque>
#include <queue>
#include <set>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <cstring>
#include <ctime>
#include <climits>
using namespace std;
#define CHECKTIME() printf("%.2lf\n", (double)clock() / CLOCKS_PER_SEC)
typedef pair<int, int> pii;
typedef long long llong;
typedef pair<llong, llong> pll;
#define mkp make_pair
/*************** Program Begin **********************/
long long dp[65][55];
vector <long long> X(60);
class PowersOfTwo {
public:
long long rec(int k, int b)
{
long long & res = dp[k][b];
if (res != -1) {
return res;
}
// base case
if (k == X.size()) {
res = 1;
return res;
}
res = 0;
int x_k = X[k] + b;
res += rec(k + 1, x_k / 2);
if (x_k > 0) {
res += rec(k + 1, (x_k - 1) / 2);
}
return res;
}
long long count(vector <long long> powers) {
long long res = 0LL;
memset(dp, -1, sizeof(dp));
for (int i = 0; i < X.size(); i++) {
X[i] = std::count(powers.begin(), powers.end(), 1LL << i);
}
res = rec(0, 0);
return res;
}
};
/************** Program End ************************/