NOIP 考前DP 复习

POJ 2533 最长不降子序列

#include <cstdio>
const int Maxn=1010;
int a[Maxn],Pos[Maxn],F[Maxn],n,Ans;
inline int Max(int x,int y) {return x>y?x:y;}
inline int Find(int x)
{
    int l=1,r=Ans,Res;
    while (l<=r)
    {
        int mid=(l+r)>>1;
        if (a[Pos[mid]]<x) Res=mid,l=mid+1;  else r=mid-1;
    }
    return Res;
}
int main()
{
    scanf("%d",&n);
    for (int i=1;i<=n;i++) scanf("%d",&a[i]);
    F[1]=1; Pos[1]=1; Ans=1;
    for (int i=2;i<=n;i++)
    {
        int t=Find(a[i]);
        Pos[t+1]=i;
        F[i]=t+1;
        Ans=Max(Ans,F[i]);
    }
    printf("%d
",Ans);
    return 0;
}

BZOJ 3886

状压DP+贪心

#include <cstdio>
#include <cstring>
const int Maxn=22;
const int Maxm=1010;
const int Inf=0x3f3f3f3f;
inline int Min(int x,int y) {return x>y?y:x;}
inline int Max(int x,int y) {return x>y?x:y;}
int n,m,f[1<<Maxn],Ans=Inf;
int Len[Maxn],P[Maxn],C[Maxn][Maxm];
int find(int x,int id)
{
    int l=0,r=P[id];
    while (l<r)
    {
        int mid=(l+r+1)>>1;
        if (C[id][mid]<=x) l=mid;
        else r=mid-1;
    }
    return l;
}
int main()
{
    // freopen("c.in","r",stdin);
    scanf("%d%d",&n,&m);
    for (int i=1;i<=n;i++)
    {
        scanf("%d%d",&Len[i],&P[i]);
        for (int j=1;j<=P[i];j++) scanf("%d",&C[i][j]);
    }
    memset(f,-1,sizeof(f)),f[0]=0;
    for (int i=0;i<(1<<n);i++)
    {
        if (f[i]==-1) continue;
        if (f[i]>=m) 
        {
            int j,k;
            for (j=0,k=i;k;k-=(k&(-k))) j++;
            Ans=Min(Ans,j);
            continue;
        }
        for (int j=1;j<=n;j++)
        {
            if (i&(1<<(j-1))) continue;
            int k=find(f[i],j);
            if (k==0) continue;
            f[i|(1<<(j-1))]=Max(f[i|(1<<(j-1))],C[j][k]+Len[j]);
        }
    }
    printf("%d
",Ans==Inf?-1:Ans);
    return 0;
}