• [国家集训队]飞飞侠


    https://www.luogu.org/problemnew/show/P4473

    仙人题啊仙人题

    正解是什么并查集优化??看不懂也不会写

    读题发现,这题的问题在于暴力建边会GG,需要解决的就是一个点向一个连通块连边的问题

    想到可以把连通块拆成一行一行,在一行内,要解决一个点向一个区间连边的问题

    线段树优化连边,我们只建维护入边的线段树,对于一个区间找到对应线段树内节点连边,树内从父亲向儿子连边(边权当然是0)

    nm个点,e=n^2mlogm = 16875000个边,这样跑一边最短路是O(eloge),似乎能过???

    然后就是我的zz时间:这个图不是无向的,因此x->y和y->x显然不同,得挨个点跑一边最短路才行...

    我好菜qaq

    2.0h

    #include<cstdio>
    #include<cstring>
    #include<algorithm>
    #include<queue>
    #include<cmath> 
    #include<iostream>
    using namespace std;
    #define O(x) cout << #x << " " << x << endl;
    #define O_(x) cout << #x << " " << x << "  ";
    #define B cout << "breakpoint" << endl;
    typedef long long ll;
    typedef pair<ll,int> pii;
    const ll inf = 1e14;
    #define mp make_pair
    inline int read()
    {
        int ans = 0,op = 1;
        char ch = getchar();
        while(ch < '0' || ch > '9')
        {
            if(ch == '-') op = -1;
            ch = getchar();
        }
        while(ch >= '0' && ch <= '9')
        {
            (ans *= 10) += ch - '0';
            ch  = getchar();
        }
        return ans * op;
    }
    const int maxn = 303;
    const int N = 1e6 + 5;
    int n,m;
    int id[maxn][maxn];//id[i][j] : i行j列对应线段树中哪个节点 
    int ls[N],rs[N],root[maxn],tot;
    struct egde
    {
      int to,next;
      ll cost;
    }e[N * 20];
    int fir[N],alloc;
    void adde(int u,int v,int w)
    {
        e[++alloc].next = fir[u];
        fir[u] = alloc;
        e[alloc].to = v;
        e[alloc].cost = w;
    }
    int build(int line,int i,int l,int r)
    {
        if(l == r)
        {
            id[line][l] = i;
            return i;
        }
        int mid = l + r >> 1;
        ls[i] = build(line,++tot,l,mid);
        rs[i] = build(line,++tot,mid + 1,r);
        adde(i,ls[i],0); adde(i,rs[i],0);
        return i;
    }
    void add(int i,int l,int r,int u,int ql,int qr,ll w)//u->[ql,qr]
    {
        if(l == ql && r == qr)
        {
            adde(u,i,w);
            return;
        }
        int mid = l + r >> 1;
        if(qr <= mid) add(ls[i],l,mid,u,ql,qr,w);
        else if(ql > mid) add(rs[i],mid + 1,r,u,ql,qr,w);
        else add(ls[i],l,mid,u,ql,mid,w),add(rs[i],mid + 1,r,u,mid + 1,qr,w); 
    }
    bool vis[N];
    ll dis[N];
    void dij(int s)
    {
            for(int i = 1;i <= tot;i++) dis[i] = inf;
        memset(vis,0,sizeof(vis));
        dis[s] = 0;
        priority_queue<pii,vector<pii>,greater<pii> > p;
        p.push(mp(dis[s],s));
        while(p.size())
        {
            pii t = p.top();
            p.pop();
            int u = t.second;
            if(vis[u]) continue;
            vis[u] = 1;
            for(int i = fir[u];i;i = e[i].next)
            {
          int v = e[i].to;
          ll w = e[i].cost;
                if(dis[v] > dis[u] + w)
                {
                    dis[v] = dis[u] + w;
                    if(!vis[v]) p.push(mp(dis[v],v));
                }
            }
        }
    }
    int b[maxn][maxn];
    ll a[maxn][maxn];
    int main()
    {
        n = read(),m = read();
        for(int i = 1;i <= n;i++) root[i] = build(i,++tot,1,m);
        for(int i = 1;i <= n;i++)
            for(int j = 1;j <= m;j++)
                b[i][j] = read();//距离 
        for(int i = 1;i <= n;i++)
            for(int j = 1;j <= m;j++)
              scanf("%lld",&a[i][j]);//费用
        for(int i = 1;i <= n;i++)
            for(int j = 1;j <= m;j++)
            {
                for(int k = max(1,i - b[i][j]);k <= min(n,i + b[i][j]);k++)
                {
                    int res = b[i][j] - abs(k - i);
                    add(root[k],1,m,id[i][j],max(1,j - res),min(m,j + res),a[i][j]);
                }
            }
        int x1 = read(),y1 = read(),x2 = read(),y2 = read(),x3 = read(),y3 = read();
        int x = id[x1][y1],y = id[x2][y2],z = id[x3][y3];
        dij(x);
        ll xy = dis[y],xz = dis[z];
        dij(y);
        ll yz = dis[z],yx = dis[x];
        dij(z);
        ll zx = dis[x],zy = dis[y];
        ll ansx = yx + zx,ansy = xy + zy,ansz = xz + yz;
        if(ansx >= inf && ansy >= inf && ansz >= inf)
          {
            printf("NO
    ");
            return 0;
          }
        if(ansx <= ansy && ansx <= ansz) printf("X
    %lld",ansx);
        else if(ansy <= ansx && ansy <= ansz) printf("Y
    %lld",ansy);
        else printf("Z
    %lld",ansz);
    }
    View Code
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  • 原文地址:https://www.cnblogs.com/LM-LBG/p/10858371.html
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