POJ–3592[Instantaneous Transference] 縮點+求最長路

思路：
(1):構完圖縮點然後求最長路
(2):注意*號的位置可以選擇不跳
(3):資料裡沒有*號跳到#號的情況

PS.說實話這題不難，思路和poj3160一樣、、

 

CODE:

/*縮點+求最長路*//*注意：*號的位置可以選擇不跳*//*AC代碼：16ms*/#include <iostream>#include <cstdio>#include <memory.h>#include <queue>#include <algorithm>#define min(a,b) (a<b?a:b)#define max(a,b) (a>b?a:b)#define MAXN 1605#define INF 1e8using namespace std;struct edge{    int u,v,w,next;}E[200000],sE[200000];int head[MAXN],ecnt;int shead[MAXN],secnt;int Low[MAXN],DFN[MAXN],Stack[MAXN],Belong[MAXN],num[MAXN];int dis[MAXN];int Index,scc,top,N,M,vn;bool Instack[MAXN],vis[MAXN];char map[50][50];int W[MAXN],scr;int ins[MAXN],cnt;void Insert(int u,int v){    E[ecnt].u=u;    E[ecnt].v=v;    E[ecnt].next=head[u];    head[u]=ecnt++;}void sInsert(int u,int v,int w){    sE[secnt].u=u;    sE[secnt].v=v;    sE[secnt].w=w;    sE[secnt].next=shead[u];    shead[u]=secnt++;}void Init(){    int i,j,u,v,x,y;    memset(head,-1,sizeof(head));ecnt=0;    memset(shead,-1,sizeof(shead));secnt=0;    memset(W,0,sizeof(W));    scanf("%d%d",&N,&M);    vn=N*M;    for(i=1;i<=N;i++)        scanf("%s",map[i]+1);    cnt=0;    for(i=1;i<=N;i++)    {        for(j=1;j<=M;j++)        {            u=(i-1)*M+j;            if(map[i][j]=='#')                W[u]=0;            else if(map[i][j]=='*')            {                W[u]=0;                ins[cnt++]=u;                if(j<M&&map[i][j+1]!='#')                    Insert(u,u+1);                if(i<N&&map[i+1][j]!='#')                    Insert(u,u+M);            }            else            {                W[u]=map[i][j]-'0';                if(j<M&&map[i][j+1]!='#')                    Insert(u,u+1);                if(i<N&&map[i+1][j]!='#')                    Insert(u,u+M);            }        }    }    /*    for(i=0;i<ecnt;i++)        printf("*%d %d\n",E[i].u,E[i].v);    */    for(i=0;i<cnt;i++)    {        scanf("%d%d",&x,&y);        x++;y++;        //if(map[x][y]=='#') continue;        v=(x-1)*M+y;        Insert(ins[i],v);    }}void Tarjan(int u){    int i,v;    Low[u]=DFN[u]=++Index;    Stack[++top]=u;    Instack[u]=true;    for(i=head[u];i!=-1;i=E[i].next)    {        v=E[i].v;        if(!DFN[v])        {            Tarjan(v);            if(Low[u]>Low[v])                Low[u]=Low[v];        }        else if(Instack[v]&&Low[u]>DFN[v])            Low[u]=DFN[v];    }    if(Low[u]==DFN[u])    {        scc++;        do{            v=Stack[top--];            Instack[v]=false;            Belong[v]=scc;            num[scc]+=W[v];        }while(u!=v);    }    return;}void Suo()//縮點+重新構圖{    int i,u,v;    memset(num,0,sizeof(num));    memset(DFN,0,sizeof(DFN));    memset(Instack,false,sizeof(Instack));    memset(Low,0,sizeof(Low));    Index=scc=top=0;    for(i=1;i<=vn;i++)//縮點    {if(!DFN[i]) Tarjan(i);}    //構新圖    for(i=0;i<ecnt;i++)    {        u=E[i].u;v=E[i].v;        if(Belong[u]!=Belong[v])            sInsert(Belong[u],Belong[v],num[Belong[v]]);    }    //printf("$%d\n",scc);}queue<int>Q;int SPFA(int s){    int i,u,v,w;    while(!Q.empty()) Q.pop();    memset(vis,false,sizeof(vis));    for(i=1;i<=scc;i++)        dis[i]=-INF;    Q.push(s);    dis[s]=0;    vis[s]=true;    while(!Q.empty())    {        u=Q.front();Q.pop();        vis[u]=false;        for(i=shead[u];i!=-1;i=sE[i].next)        {            v=sE[i].v;w=sE[i].w;            if(dis[v]<dis[u]+w)            {                dis[v]=dis[u]+w;                if(!vis[v])                {                    Q.push(v);                    vis[v]=true;                }            }        }    }    int res=0;    for(i=1;i<=scc;i++)        res=max(res,dis[i]);    return res+num[s];}void Solve(){    Suo();    scr=Belong[1];    int ans=SPFA(scr);    printf("%d\n",ans);}int main(){    int T;    scanf("%d",&T);    while(T--)    {        Init();        Solve();    }return 0;}