• 2017.10.23 模拟赛


    题目链接

    T1

    模拟

    #include <algorithm>
    #include <cstring>
    #include <cstdio>
    #define N 100005
    struct node
    {
        int x,y;
        bool operator<(node a)const
        {
            return x<a.x;
        }
    }pp[N];
    int len,sum,tot=1;
    char str[N];
    int main(int argc,char *argv[])
    {
        freopen("cross.in","r",stdin);
        freopen("cross.out","w",stdout);
        scanf("%s",str+1);
        len=strlen(str+1);
        for(register int i=0;i<=25;++i)
        {
            for(register int j=1;j<=len;++j)
            {
                if(i==str[j]-'a')
                {
                    if(pp[tot].y) pp[++tot].x=j;
                    else
                    {
                        if(!pp[tot].x) pp[tot].x=j;
                        else pp[tot].y=j;
                    }
                }
            }
        }
        std::sort(pp+1,pp+1+tot);
        for(register int i=1;i<=tot;++i)
        {
            int x1=pp[i].x,y1=pp[i].y;
            for(register int j=i+1;j<=tot;++j)
            {
                int x2=pp[j].x,y2=pp[j].y;
                if(x2>y1) break;
                if((x2>x1&&x2<y1&&y2>y1)) sum++;
            }
        }
        printf("%d
    ",sum);
        fclose(stdin); fclose(stdout);
        return 0;
    }
    View Code

    T2

    二分+dijkstra 85分

    正解不知道是啥

    #include <cstring>
    #include <cstdio>
    #include <queue>
    #define N 4005
    #define inf 0x3f3f3f3f
    using namespace std;
    bool vis[N<<1],tp[505][505];
    int n,m,q,k,cnt,ans=inf,far[N],to[N<<1],pre[N],head[N<<1],nextt[N<<1],val[N<<1],opt[N<<1];
    struct node
    {
        int x,y;
        bool operator<(node a)const
        {
            return y>a.y;
        }
    };
    priority_queue<node>Q;
    inline int min(int a,int b) {return a>b?b:a;}
    bool check(int x)
    {
        int use=0;
        for(register int i=1;i<=n;++i) vis[i]=false,far[i]=inf;
        far[1]=0;
        Q.push((node){1,far[1]});
        for(node now;!Q.empty();)
        {
            now=Q.top();Q.pop();
            if(vis[now.x]) continue;
            vis[now.x]=true;
            for(register int i=head[now.x];i;i=nextt[i])
            {
                int v=to[i];
                if(far[v]>far[now.x]+val[i]&&opt[i]==1)
                {
                    far[v]=far[now.x]+val[i];
                    pre[v]=now.x;
                    if(!vis[v]) Q.push((node){v,far[v]});
                }
                else if(far[v]>far[now.x]+val[i]&&opt[i]==2&&val[i]<=x)
                {
                    far[v]=far[now.x]+val[i];
                    pre[v]=now.x;
                    if(!vis[v]) Q.push((node){v,far[v]});
                }
            }
        }
        for(register int i=n;pre[i];i=pre[i]) if(tp[pre[i]][i]) use++;
        if(use<=k) {ans=min(ans,far[n]);return true;}
        return false;
    }
    int main(int argc,char *argv[])
    {
        freopen("move.in","r",stdin);
        freopen("move.out","w",stdout);
        scanf("%d%d%d%d",&n,&m,&q,&k);
        for(int u,v,w;m--;)
        {
            scanf("%d%d%d",&u,&v,&w);
            nextt[++cnt]=head[u];to[cnt]=v;val[cnt]=w;
            head[u]=cnt;opt[cnt]=1;
        }
        for(int u,v,w;q--;)
        {
            scanf("%d%d%d",&u,&v,&w);
            nextt[++cnt]=head[u];to[cnt]=v;val[cnt]=w;
            head[u]=cnt;opt[cnt]=2;
            tp[u][v]=1;
        }
        if(!k) {check(0) ;printf("%d
    ",ans);return 0;} 
        int l=0,r=inf;
        for(register int mid;l<=r;)
        {
            mid=(l+r)>>1;
            if(check(mid)) l=mid+1;
            else r=mid-1;
        }
        printf("%d
    ",ans);
        fclose(stdin);fclose(stdout);
        return 0;
    }
    二分+dijkstra
    #include <iostream>
    #include <cstdlib>
    #include <cstring>
    #include <cstdio>
    #include <queue>
    #include <vector>
    
    using namespace std;
    
    namespace Solve
    {
        typedef pair<int,int> Node;
        const int MAXN = 500 + 10, MAXM = 2000 + 10, INF = 0x7fffffff/2;
        int n, m, q, k;
        int nodes[MAXN][MAXN], nop;
        int head[MAXN*MAXN], next[MAXN*MAXM*2], to[MAXN*MAXM*2], w[MAXN*MAXM*2], op;
        int dis[MAXN*MAXN];
    
        void build(int a, int b, int x)
        {
            next[++op]=head[a];head[a]=op;to[op]=b;w[op]=x;
        }
        int dijkstra(int s, int t, int n)
        {
            priority_queue<Node, vector<Node>, greater<Node> > que;
            
            for(int i=1;i<=n;i++) dis[i] = INF;
            dis[s] = 0;
            que.push(Node(dis[s], s));
            while(!que.empty())
            {
                Node u = que.top(); que.pop();
                if (dis[u.second] != u.first) continue;
                for(int pos=head[u.second]; pos; pos=next[pos])
                {
                    if (u.first + w[pos] < dis[to[pos]])
                    {
                        dis[to[pos]] = u.first + w[pos];
                        que.push(Node(dis[to[pos]], to[pos]));
                    }
                }
            }
    
            return dis[t] == INF ? -1 : dis[t];
        }
        void solve()
        {
            scanf("%d%d%d%d", &n, &m, &q, &k);
            k = min(k, n);
    
            nop = 0;
            for(int i=0;i<=k;i++)
                for(int u=1;u<=n;u++)
                    nodes[i][u] = ++nop;
    
            for(int i=1;i<=m;i++)
            {
                int u, v, w;
                scanf("%d%d%d", &u, &v, &w);
                for(int j=0;j<=k;j++)
                    build(nodes[j][u], nodes[j][v], w);
            }
    
            for(int i=1;i<=q;i++)
            {
                int x, y, z;
                scanf("%d%d%d", &x, &y, &z);
                for(int j=0;j<k;j++)
                    build(nodes[j][x], nodes[j+1][y], z);
            }
    
            for(int i=0;i<k;i++)
                build(nodes[i][n], nodes[i+1][n], 0);
            
            cout << dijkstra(nodes[0][1], nodes[k][n], nop) << endl;
        }
    }
    
    int main()
    {
        freopen("move.in", "r", stdin);
        freopen("move.out", "w", stdout);
    
        Solve::solve();
    
        return 0;
    }
    std

    T3

    20分乱搞

    正解树形dp

    #include <cstring>
    #include <cstdio>
    #include <set>
    #define N 5005
    #define Mod 786433
    
    using namespace std;
    set<int>se;
    struct node
    {
        int x,y;
    }e[N];
    bool V[N<<1],fw[N];
    int n,k,cnt=1,tim,tot,ans,num[N<<1],id[N<<1],fa[N],to[N<<1],siz[N<<1],head[N],nextt[N<<1];
    void Dfs1(int x,int pre)
    {
        siz[x]=1;
        fw[x]=true;
        for(int i=head[x];i;i=nextt[i])
        {
            int v=to[i];
            if(v==pre||fw[v]) continue;
            Dfs1(v,x);
            siz[x]+=siz[v];
        }
    }
    void Dfs2(int x,int pre)
    {
        fw[x]=true;
        for(int i=head[x];i;i=nextt[i])
        {
            int v=to[i];
            if(siz[v]>=k&&!V[id[i^1]]&&!V[id[i]]) num[++tot]=id[i],V[id[i]]=true,V[id[i^1]]=true;
            if(v==pre||fw[v]) continue;
            Dfs2(v,x);
        }
    }
    int find_(int x) {return x==fa[x]?x:fa[x]=find_(fa[x]);}
    bool check()
    {
        int Size[N];
        for(int i=1;i<=n;++i) fa[i]=i,Size[i]=0;
        for(int i=1;i<n;++i)
        {
            if(se.find(i)!=se.end()) continue;
            fa[find_(e[i].y)]=find_(e[i].x);
        }
        for(int i=1;i<=n;++i) Size[fa[find_(i)]]++;
        for(int i=1;i<=n;++i)
            if(Size[fa[find_(i)]]<k) return false;
        return true; 
    }
    void Dfs3(int p)
    {
        if(p>tot) return;
        if(check()) ans=(ans+1)%Mod;
        for(int i=p+1;i<=tot;++i)
        {
            se.insert(num[i]);
            Dfs3(i);
            se.erase(num[i]);  
        }
    }
    inline void swap(int &m,int &n)
    {
        int tmp=n;
        n=m;
        m=tmp;
    }
    int main(int argc,char *argv[])
    {
        freopen("cut.in","r",stdin);
        freopen("cut.out","w",stdout);
        scanf("%d%d",&n,&k);
        for(int u,v,i=1;i<n;++i)
        {
            scanf("%d%d",&u,&v);
            if(u>v) swap(u,v);
            nextt[++cnt]=head[u];to[cnt]=v;head[u]=cnt;id[cnt]=i;
            nextt[++cnt]=head[v];to[cnt]=u;head[v]=cnt;id[cnt]=i;
            e[i]=(node){u,v};
        }
        Dfs1(1,0);
        memset(fw,0,sizeof(fw));
        Dfs2(1,0);
        Dfs3(0);
        printf("%d
    ",ans);
        fclose(stdin); fclose(stdout);
        return 0;
    }
    乱搞20
    #include<cstdio>
    #include<cstdlib>
    #define N 5555
    #define M 786433
    using namespace std;
    typedef long long LL;
    struct edge
    {
        int t,n;
    }e[N*2];
    LL h[N],size[N],f[N][N],g[N],cnt[N];
    int n,K,tote;
    void add(int u,int v)
    {
        e[++tote].t=v;
        e[tote].n=h[u];
        h[u]=tote;
        return ;
    }
    void dfs(int u,int fa)
    {
        size[u]++; f[u][1]=1;
        for (int i=h[u];i;i=e[i].n)
        {
            int v=e[i].t;
            if (v==fa) continue;
            dfs(v,u);
            for (int j=1;j<=size[u]+size[v];j++) g[j]=0;
            for (int j=1;j<=size[u];j++) g[j]=cnt[v]*f[u][j]%M;
            for (int j=1;j<=size[u];j++)
            for (int k=1;k<=size[v];k++) g[j+k]=(g[j+k]+f[u][j]*f[v][k]%M)%M;
            for (int j=1;j<=size[u]+size[v];j++) f[u][j]=g[j];
            size[u]+=size[v];
        }
        for (int i=K;i<=size[u];i++) cnt[u]=(cnt[u]+f[u][i])%M;
        return ;
    }
    int main()
    {
        freopen("cut.in","r",stdin);
        freopen("cut.out","w",stdout);
        scanf("%d %d",&n,&K);
        for (int i=1;i<n;i++)
        {
            int u,v;
            scanf("%d %d",&u,&v);
            add(u,v); add(v,u);
        }
        dfs(1,1);
        printf("%d
    ",cnt[1]);
        fclose(stdin);
        fclose(stdout);
        return 0;
    }
    std
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  • 原文地址:https://www.cnblogs.com/ruojisun/p/7716746.html
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