687C - The Values You Can Make

bitset优化背包

#include<iostream>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<cstdlib>
#include<climits>
#include<stack>
#include<vector>
#include<queue>
#include<set>
#include<bitset>
#include<map>
//#include<regex>
#include<cstdio>
#pragma GCC optimize(2)
#define up(i,a,b)  for(int i=a;i<b;i++)
#define dw(i,a,b)  for(int i=a;i>b;i--)
#define upd(i,a,b) for(int i=a;i<=b;i++)
#define dwd(i,a,b) for(int i=a;i>=b;i--)
//#define local
typedef long long ll;
typedef unsigned long long ull;
const double esp = 1e-6;
const double pi = acos(-1.0);
const int INF = 0x3f3f3f3f;
const int inf = 1e9;
using namespace std;
ll read()
{
	char ch = getchar(); ll x = 0, f = 1;
	while (ch<'0' || ch>'9') { if (ch == '-')f = -1; ch = getchar(); }
	while (ch >= '0' && ch <= '9') { x = x * 10 + ch - '0'; ch = getchar(); }
	return x * f;
}
typedef pair<int, int> pir;
#define lson l,mid,root<<1
#define rson mid+1,r,root<<1|1
#define lrt root<<1
#define rrt root<<1|1
const int N = 519;
bitset<N>bits[N];
int n, k;
int dp[N];
int c[N];
int main()
{
	dp[0] = 1;
	n = read(), k = read();
	upd(i, 1, n)
		c[i] = read();
	sort(c + 1, c + n + 1);
	upd(i, 1, n)
	{
		 dwd(j,500,0)
		 {
			if (j + c[i] > k)continue;
			if (!dp[j])continue;
			dp[j + c[i]] = 1;
			bits[j + c[i]] |= bits[j] << (c[i]);
			bits[j + c[i]] |= bits[j];
			bits[j + c[i]].set(c[i]);
		}
	}
	bits[k].set(0);
	string s = bits[k].to_string();
	reverse(s.begin(), s.end());
	int cnt = 0;
	vector<int>ans;
	upd(i, 0, k)
	{
		if (s[i] == '1')
		{
			cnt++;
			ans.push_back(i);
		}
	}
	cout << cnt << endl;
	for (auto k: ans)
	{
		cout << k << " ";
	}
	return 0;
}