[BZOJ2464]中山市选[2009]小明的游戏

原题地址

刷水ing…

AC code:

#include <cstdio>#include <vector>#include <queue>using namespace std;const int N=501;const int INF=1<<29;int  n,m,x1,y1,x2,y2,S,T;int  mx[5]={0,1,-1,0,0},my[5]={0,0,0,1,-1},minw[N*N];bool inq[N*N];char s[N][N];struct Data{    int v,w;    Data() {}    Data(int v,int w):v(v),w(w) {}};vector<Data> G[N*N];int Num(int x,int y){    return (x-1)*m+y;}int Abs(int x){    return x<0?-x:x;}void SPFA(){    queue<int> Q;    for(int i=1;i<=Num(n,m);i++) minw[i]=INF;    minw[S]=0;Q.push(S);    while(!Q.empty()){        int x=Q.front();        Q.pop();inq[x]=0;        for(int i=0;i<(int)G[x].size();i++){            int v=G[x][i].v,w=G[x][i].w;            if(minw[x]+w>=minw[v]) continue;            minw[v]=minw[x]+w;            if(!inq[v]){                inq[v]=1;                Q.push(v);            }        }    }    for(int i=1;i<=Num(n,m);i++) G[i].clear();}int main(){    while(1){        scanf("%d%d",&n,&m);        if(n==0&&m==0) break;        for(int i=1;i<=n;i++) scanf("%s",s[i]);        for(int i=1;i<=n;i++){            for(int j=0;j<m;j++){                for(int k=1;k<=4;k++){                    int ii=i+mx[k],jj=j+my[k];                    if(ii<1||ii>n||jj<0||jj>=m) continue;                    G[Num(i,j+1)].push_back(Data(Num(ii,jj+1),s[i][j]==s[ii][jj]?0:1));                }            }        }        scanf("%d%d%d%d",&x1,&y1,&x2,&y2);        S=Num(x1+1,y1+1);T=Num(x2+1,y2+1);        SPFA();        printf("%d\n",minw[T]);    }    return 0;}