POJ - 3057 Evacuation

//注意D和D之间不能扩展啊
#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#define ll long long
using namespace std;
ll read() {
    ll x=0,f=1;
    char ch=getchar();
    while(!(ch>=‘0‘&&ch<=‘9‘)) {
        if(ch==‘-‘)f=-1;
        ch=getchar();
    };
    while(ch>=‘0‘&&ch<=‘9‘) {
        x=x*10+(ch-‘0‘);
        ch=getchar();
    };
    return x*f;
}
const int MAXN = 550*20*4;//??????
const int MAXM = 550*550*20*4;//??????
struct Edge {
    int to,next;
} edge[MAXM];
int head[MAXN],tot;
void init() {
    tot = 0;
    memset(head,-1,sizeof(head));
}
void addedge(int u,int v) {
    edge[tot].to = v;
    edge[tot].next = head[u];
    head[u] = tot++;
}
int linker[MAXN];
bool used[MAXN];
int uN;
struct dat{
    int tm;
    int x;
    int y;
    int id;
}tmp,nxt;
int nn,mm,lm;
char mp[20][20];
queue<dat> q;
int cntd,xd[MAXN],yd[MAXN];
bool dfs(int u) {
    for(int i = head[u]; i != -1 ; i = edge[i].next) {
        int v = edge[i].to;
        if(!used[v]) {
            used[v] = true;
            if(linker[v] == -1 || dfs(linker[v])) {
                linker[v] = u;
                return true;
            }
        }
    }
    return false;
}
int hungary() {
    int res = 0;
    memset(linker,-1,sizeof(linker));
    for(int u = 0; u <= lm*cntd; u++) {
        memset(used,false,sizeof(used));
        if(dfs(u))res++;
    }
    return res;
}
bool cmp(int a,int b){
    return a > b;
}

bool viss[100][20][20];
int dx[4] = {-1,0,1,0};
int dy[4] = {0,-1,0,1};
int tj;
bool judge(int y,int x){
    if(y < 1 || y > nn || x < 1 || x > mm || mp[y][x] == ‘X‘ || mp[y][x] == ‘D‘) return false;
    return true;
}
void bfs(){
    tj = 0;
    cntd = 0;
    memset(viss,false,sizeof(viss));
    lm = nn*mm;
    int hh;
    while(!q.empty()) q.pop();
    for(int i = 1;i <= nn;i++){
        for(int j = 1;j <= mm;j++){
            if(mp[i][j] == ‘D‘){
                cntd++;
                xd[cntd] = j;
                yd[cntd] = i;
            }else if(mp[i][j] == ‘.‘){
                tj++;
            }
        }
    }
    for(int i = 1;i <= cntd;i++){
        tmp.id = i;
        tmp.tm = 0;
        tmp.y = yd[i];
        tmp.x = xd[i];
        viss[tmp.id][tmp.y][tmp.x] = true;
        q.push(tmp);
    }
    while(!q.empty()){
        
        tmp = q.front();
        q.pop();
        for(int k = 0;k < 4;k++){
            nxt.id = tmp.id;
            nxt.tm = tmp.tm + 1;
            nxt.y = tmp.y + dy[k];
            nxt.x = tmp.x + dx[k];
            if(!judge(nxt.y,nxt.x)) continue;
            if(viss[nxt.id][nxt.y][nxt.x]) continue;
            if(mp[nxt.y][nxt.x] == ‘.‘){ 
            hh = nxt.tm;
                for(;hh <= lm;hh++)addedge((hh-1)*cntd+nxt.id-1,(nxt.y-1)*mm+nxt.x-1);
            }
            viss[nxt.id][nxt.y][nxt.x] = true;
            q.push(nxt);
        }
    }
}

int main() {
    int T,ans;
    cin>>T;
    while(T--) {
        init();
        nn = read();
        mm = read();
        
        for(int i = 1;i <= nn;i++){
            scanf("%s",mp[i]+1);
        }
        
        bfs();
        ans = hungary();
        if(ans != tj){
            cout<<"impossible"<<endl;
            continue;
        }
        ans = 0;
        for(int i = 0;i <= lm;i++){
            if(linker[i] != -1){
                //cout<<i/mm+1<<" "<<i%mm+1<<" "<<yd[linker[i]%cntd]<<" "<<xd[linker[i]%cntd]<<" "<<linker[i]/cntd+1<<endl;
                ans = max(linker[i]/cntd+1,ans);
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}