UVA 1078 dij模板

Posted 2020-07-24 iEdson

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <stack>
#include <string>
#include <queue>
#include <vector>
#include <algorithm>
#include <ctime>
using namespace std;

//#define EdsonLin

#ifdef EdsonLin
#define debug(...) fprintf(stderr,__VA_ARGS__)
#else
#define debug(...)
#endif //EdsonLin

typedef long long ll;
typedef double db;
const int inf = 0x3f3f3f;
const int MAXN = 110;
const int MAXNN = 5e4+10;
//const int MAXM = 3e4+100;
const int MOD = 1000000007;
const db eps = 1e-3;
#define PB push_back

struct dij{
    int n,m;
    int first[MAXNN];
    struct edge{
        int st,to,next,dist;
    };
    vector<edge>e;
    int top;
    int d[MAXNN]; //s到各节点的距离
    int done[MAXNN]; //是否已经被永久标记
    int p[MAXNN]; //记录上一条边
    struct heapnode{
        int st;
        int dist;
        bool operator < (const heapnode& rhs) const {
            return dist>rhs.dist;
        }
    };
    void init(int n){
        this->n = n;
        memset(first,-1,sizeof(first));
        top = 0;
        e.clear();
    }
    void addedge(int u,int v,int dist){
        /*e[top].st = u;
        e[top].to = v;
        e[top].dist = dist;
        e[top].next = first[u];
        first[u] = top++;*/
        //if(u==0)cout<<dist<<endl;
        edge a;
        a.st = u;
        a.to = v;
        a.dist = dist;
        a.next  = first[u];
        e.PB(a);
        first[u] = top++;
        //cout<<first[u]<<endl;
       // cout<<top<<endl;
    }

    void pqdij(int s){
        priority_queue<heapnode>Q;
        heapnode a;
        for(int i=0;i<n;i++)
            d[i] = inf;
        d[s] = 0;
        memset(done,0,sizeof(done));
        a.dist = 0;
        a.st = s;
        Q.push(a);
        while(!Q.empty()){
            heapnode x = Q.top();
            Q.pop();
            int u = x.st;
            if(done[u])continue;
            done[u] = 1;
            //debug("Edson:%d\\n",u);
            for(int i=first[u];i!=-1;i=e[i].next){
                if(d[e[i].to]>d[u]+e[i].dist){
                    d[e[i].to] = d[u] + e[i].dist;
                    p[e[i].to] = i;
                    a.dist = d[e[i].to];
                    a.st = e[i].to;
                    Q.push(a);
                }
            }
        }
    }
}solver;

const int UP = 0,LEFT = 1,DOWN = 2,RIGHT = 3;
const int inv[] = {2,3,0,1};
const int dr[] = {-1,0,1,0};
const int dc[] = {0,-1,0,1};

int grid[MAXN][MAXN][4];
int id[MAXN][MAXN][5];
int idn;
int n,m,rs,cs,re,ce;

int ID(int r,int c,int dir){
    int&x = id[r][c][dir];
    if(x==0)x = ++idn;
    return x;
}

int readint(){int x;scanf("%d",&x);return x;}

bool cango(int r,int c,int dir){
    if(r<0||r>=n||c<0||c>=m)return false;
    return grid[r][c][dir]>0;
}

int main()
{
    //cout<<inf<<endl;
    #ifdef EdsonLin
        //freopen("1.in","r",stdin);
        //freopen("1.out","w",stdout);
        int _time_ed = clock();
    #endif //EdsonLin
    int mc = 0;
    while(cin>>n>>m>>rs>>cs>>re>>ce,n){
        rs--;cs--;re--;ce--;
        for(int i=0;i<n;i++){
            for(int j=0;j<m-1;j++){
                grid[i][j][RIGHT] = grid[i][j+1][LEFT] = readint();
            }
            if(i!=n-1)
                for(int j=0;j<m;j++){
                    grid[i][j][DOWN] = grid[i+1][j][UP] = readint();
                }
        }

        idn = 0;
        memset(id,0,sizeof(id));
        solver.init(n*m*5+1);
        /*cout<<grid[0][0][RIGHT]<<endl;*/
        for(int dir=0;dir<4;dir++){
            if(cango(rs,cs,dir)){
                solver.addedge(0,ID(rs+dr[dir],cs+dc[dir],dir),grid[rs][cs][dir]*2);
                solver.addedge(0,ID(rs+dr[dir],cs+dc[dir],4),grid[rs][cs][dir]*2);
            }
        }

        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                for(int dir=0;dir<4;dir++)if(cango(i,j,inv[dir])){
                    solver.addedge(ID(i,j,dir),ID(i,j,4),grid[i][j][inv[dir]]);
                    if(cango(i,j,dir))
                        solver.addedge(ID(i,j,dir),ID(i+dr[dir],j+dc[dir],dir),grid[i][j][dir]);
                }
                for(int dir=0;dir<4;dir++)if(cango(i,j,dir)){
                    solver.addedge(ID(i,j,4),ID(i+dr[dir],j+dc[dir],dir),grid[i][j][dir]*2);
                    solver.addedge(ID(i,j,4),ID(i+dr[dir],j+dc[dir],4),grid[i][j][dir]*2);
                }
            }
        }

        solver.pqdij(0);

        int ans = solver.d[ID(re,ce,4)];
        printf("Case %d: ",++mc);
        if(ans==inf)printf("Impossible\\n");else printf("%d\\n",ans);
    }


    #ifdef EdsonLin
        debug("time: %d\\n",int(clock()-_time_ed));
    #endif //EdsonLin
   // cout << "Hello world!" << endl;
    return 0;
}

RT