CodeForces755F 贪心 + 多重背包二进制优化

#include <map>
#include <set>
#include <ctime>
#include <bitset>
#include <cmath>
#include <queue>
#include <stack>
#include <vector>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;
#define For(i, x, y) for(int i=x;i<=y;i++)  
#define _For(i, x, y) for(int i=x;i>=y;i--)
#define Mem(f, x) memset(f,x,sizeof(f))  
#define Sca(x) scanf("%d", &x)
#define Sca2(x,y) scanf("%d%d",&x,&y)
#define Scl(x) scanf("%lld",&x);  
#define Pri(x) printf("%d\n", x)
#define Prl(x) printf("%lld\n",x);  
#define CLR(u) for(int i=0;i<=N;i++)u[i].clear();
#define LL long long
#define ULL unsigned long long  
#define mp make_pair
#define PII pair<int,int>
#define PIL pair<int,long long>
#define PLL pair<long long,long long>
#define pb push_back
#define fi first
#define se second 
typedef vector<int> VI;
const double eps = 1e-9;
const int maxn = 1e6 + 10;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + 7; 
int N,M,tmp,K; 
int tree[maxn];
int SIZE[maxn];
int a[maxn];
void init(){
    For(i,1,N) tree[i] = i,SIZE[i] = 1;
}
int find(int t){
    if(t == tree[t]) return t;
    return t = find(tree[t]);
}
void Union(int a,int b){
    a = find(a); b = find(b);
    if(a == b) return;
    tree[a] = b;
    SIZE[b] += SIZE[a];
}
vector<int>bag;
vector<int>W;
int num[maxn];
bool dp[maxn];
int main()
{
    Sca2(N,K);
    init();
    For(i,1,N){
        Sca(a[i]); 
        Union(i,a[i]);
    } 
    For(i,1,N) if(tree[i] == i) bag.pb(SIZE[i]);
    int cnt = 0,tot = 0;
    for(int i = 0; i < bag.size(); i++){
        if(bag[i] % 2){
            cnt++;
            tot += bag[i] / 2;
        }else{
            tot += bag[i] / 2;
        }
    }
    int MIN,MAX;
    if(K <= tot) MAX = K * 2;
    else MAX = tot * 2 + min(cnt,K - tot);
    for(int i = 0; i < bag.size(); i ++){
        num[bag[i]]++;
    }
    for(int i = 0 ; i < maxn; i ++){
        int k = 1;
        while(num[i] >= k){
            W.pb(i * k);
            num[i] -= k;
            k <<= 1;
        }
        if(num[i]){
            W.pb(i * num[i]);
        } 
    }
    dp[0] = 1;
    for(int i = 0 ; i < W.size(); i ++){
        int t = W[i];
        for(int j = K; j >= t ;j --){
            if(dp[j - t]) dp[j] = 1;
        }
    }
    if(dp[K]) MIN = K;
    else MIN = K + 1;
    printf("%d %d",MIN,MAX);
    #ifdef VSCode
    system("pause");
    #endif
    return 0;
}