UVALive-6665-Dragons Cruller(Dij+Hash)

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将所有的康托展开扫一遍，然后逆康托展开，以此求转移权值

然后建图，只需要建一次图，因为状态转移是固定的

然后每一次询问跑一次最短路就行

（有一部分人用的是BFS+hash，

（有一部分人用的是A*

一开始上面两种思路觉得都会TLE，但是最后大家都没有...感谢大A熊的代码

#include <iostream>#include <cstdio>#include <queue>#include <algorithm>#include <cstring>#include <cstdlib>#include <ctime>#define maxn 500005#define inf 10000000using namespace std;int fac[12] = {1,1,2,6,24,120,720,5040,40320,362880,3628800,39916800};int b[12] = {0,1,2,3,4,5,6,7,8,9,10,11};int Hash(int s[],int fac[],int len){    int ktzk = 0;    for(int i = 0;i < len;i++)    {        int cnt = 0;        for(int j=i+1;j<len;j++)            if(s[j]<s[i]) cnt++;        ktzk+=fac[len - 1 - i]*cnt;    }    return ktzk;}void get_ans(int result[],int b[],int fac[],int len,int n){    for(int i=0;i<12;i++) b[i] = i;    for(int j=0;j<len;j++)    {        int temp = n/fac[len - 1 - j];        result[j] = b[temp];        for(int i=temp;i<len-1;i++)            b[i] = b[i+1];        n -= temp*fac[len - 1 - j];    }}int head[maxn],next[4*maxn],node[4*maxn],val[4*maxn];int ch,cv,start,target,Index;int T[9];int MaxIndex;void Init(){    memset(head,0,sizeof(head));    memset(next,0,sizeof(next));    Index = 0;}void Addedge(int from,int to,int v){    Index++;    next[Index] = head[from];    node[Index] = to;    val[Index] = v;    head[from] = Index;}struct HeapNode{    int d,u;    bool operator <(const HeapNode & rhs) const    {        return d > rhs.d;    }};bool vis[maxn];int d[maxn];int Dij(int s,int t){    priority_queue<HeapNode> Q;    for(int i=0;i<=MaxIndex;i++) d[i] = inf;    d[s] = 0;    memset(vis,false,sizeof(vis));    Q.push((HeapNode){0,s});    while(!Q.empty())    {        HeapNode x = Q.top();Q.pop();        int u = x.u;        if(u == t) return d[u];        if(vis[u]) continue;        vis[u] = true;        for(int p = head[u];p;p=next[p])        {            if(d[ node[p] ]>d[u]+(val[p]==0?ch:cv))            {                d[node[p]] = d[u] + (val[p]==0?ch:cv);                Q.push((HeapNode){d[node[p]],node[p]});            }        }    }}int main(){    int MaxT[9] = {8,7,6,5,4,3,2,1,0};    MaxIndex = Hash(MaxT,fac,9);    Init();    for(int i=0;i<=MaxIndex;i++)    {        int T1[12],T2[12];        get_ans(T1,b,fac,9,i);        int pos,to;        for(int j=0;j<9;j++) if(T1[j] == 0) pos = j;//Sleep(500);        for(int j=0;j<9;j++) T2[j] = T1[j];        swap(T2[pos],T2[(pos+1)%9]);        to = Hash(T2,fac,9);        Addedge(i,to,0);//cout<<i<<' '<<to<<' '<<ch<<endl;        for(int j=0;j<9;j++) T2[j] = T1[j];        swap(T2[pos],T2[(pos+8)%9]);        to = Hash(T2,fac,9);        Addedge(i,to,0);//cout<<i<<' '<<to<<' '<<ch<<endl;        for(int j=0;j<9;j++) T2[j] = T1[j];        swap(T2[pos],T2[(pos+3)%9]);        to = Hash(T2,fac,9);        Addedge(i,to,1);//cout<<i<<' '<<to<<' '<<ch<<endl;        for(int j=0;j<9;j++) T2[j] = T1[j];        swap(T2[pos],T2[(pos+6)%9]);        to = Hash(T2,fac,9);        Addedge(i,to,1);//cout<<i<<' '<<to<<' '<<ch<<endl;    }    while(1)    {        scanf("%d%d",&ch,&cv);        if(ch == 0 && cv == 0) break;        for(int i=0;i<9;i++) scanf("%d",&T[i]);        start = Hash(T,fac,9);        for(int i=0;i<9;i++) scanf("%d",&T[i]);        target = Hash(T,fac,9);//cout<<start<<' '<<target<<endl;        cout<<Dij(start,target)<<endl;    }    return 0;}

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