【HDOJ】2732 Leapin' Lizards

贪心+网络流。对于每个结点，构建入点和出点。
对于每一个lizard>0,构建边s->in position of lizard， 容量为1.
对于pillar>0, 构建边in position of pillar -> out position of pillar, 容量为number of pillar.
若沿四个方向移动距离d可以超过边界，则构建边out position of pillar -> t， 容量为INF；
否则， 对于曼哈顿距离l(l>0 and l<=d)的点p构建边out position of pillar -> in position p, 容量为INF。（此时，不用考虑p是否含有pillar，无所谓）
Dinic可解网络流。一定要注意输出was/were，单复数和0等。

 /* 2732 */
 #include <iostream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <stack>
 #include <vector>
 #include <deque>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <ctime>
 #include <cstring>
 #include <climits>
 #include <cctype>
 #include <cassert>
 #include <functional>
 #include <iterator>
 #include <iomanip>
 using namespace std;
 //#pragma comment(linker,"/STACK:102400000,1024000")

 #define sti                set<int>
 #define stpii            set<pair<int, int> >
 #define mpii            map<int,int>
 #define vi                vector<int>
 #define pii                pair<int,int>
 #define vpii            vector<pair<int,int> >
 #define rep(i, a, n)     for (int i=a;i<n;++i)
 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 #define clr                clear
 #define pb                 push_back
 #define mp                 make_pair
 #define fir                first
 #define sec                second
 #define all(x)             (x).begin(),(x).end()
 #define SZ(x)             ((int)(x).size())
 #define lson            l, mid, rt<<1
 #define rson            mid+1, r, rt<<1|1

 const int INF = 0x1f1f1f1f;
 const int maxn = ;
 const int maxv = maxn*maxn*;
 const int maxe = maxv*maxn*;
 int V[maxe], F[maxe], nxt[maxe];
 int head[maxv], dis[maxv];
 char Ps[maxn][maxn], Ls[maxn][maxn];
 int dir[][] = {
     -, , , , , -, ,
 };
 int n, m;

 void addEdge(int u, int v, int c) {
     V[m] = v;
     F[m] = c;
     nxt[m] = head[u];
     head[u] = m++;

     V[m] = u;
     F[m] = ;
     nxt[m] = head[v];
     head[v] = m++;
 }

 bool bfs(int s, int t) {
     queue<int> Q;
     int u, v, k;

     memset(dis, , sizeof(dis));
     Q.push(s);
     dis[s] = ;

     while (!Q.empty()) {
         u = Q.front();
         Q.pop();
         for (k=head[u]; k!=-; k=nxt[k]) {
             v = V[k];
             if (!dis[v] && F[k]) {
                 dis[v] = dis[u] + ;
                 Q.push(v);
             }
         }
     }

     return dis[t]==;
 }

 int dfs(int u, int t, int val) {
     if (u==t || val==)
         return val;

     int ret = ;
     int tmp, v, k;

     for (k=head[u]; k!=-; k=nxt[k]) {
         v = V[k];
         if (dis[v]==dis[u]+ && F[k] && (tmp=dfs(v, t, min(val, F[k])))>) {
             F[k] -= tmp;
             F[k^] += tmp;
             ret += tmp;
             val -= tmp;
             if (val == )
                 break;
         }
     }

     return ret;
 }

 int Dinic(int s, int t) {
     int ret = , tmp;

     while () {
         if (bfs(s, t))
             break;

         tmp = dfs(s, t, INF);
         ret += tmp;
     }

     return ret;
 }

 int main() {
     ios::sync_with_stdio(false);
     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     int case_n;
     int s, t, n_, m_, d, tmp;
     int x, y;
     int k, id, id_;
     int ans, tot;
     bool flag;

     scanf("%d", &case_n);
     rep(tt, , case_n+) {
         scanf("%d %d", &n_, &d);

         rep(i, , n_+)
             scanf("%s", Ps[i]+);
         rep(i, , n_+)
             scanf("%s", Ls[i]+);

         m_ = strlen(Ps[]+);
         tot = ;
         s = m = ;
         k = n_ * m_;
         t = k*+;
         memset(head, -, sizeof(head));

         rep(i, , n_+) {
             rep(j, , m_+) {
                 id = (i-) * m_ + j;
                 if (Ls[i][j] == 'L') {
                     addEdge(s, id, );
                     ++tot;
                 }
                 if (Ps[i][j] > '') {
                     addEdge(id, id+k, Ps[i][j]-'');
                     flag = true;
                     id += k;
                     rep(kk, , ) {
                         x = i + dir[kk][] * d;
                         y = j + dir[kk][] * d;
                         if (x<= || x>n_ || y<= || y>m_) {
                             addEdge(id, t, INF);
                             flag = false;
                             break;
                         }
                     }
                     if (flag) {
                         id_ = ;
                         rep(ii, , n_+) {
                             rep(jj, , m_+) {
                                 ++id_;
                                 tmp = abs(ii-i) + abs(jj-j);
                                 if (tmp> && tmp<=d)
                                     addEdge(id, id_, Ps[i][j]-'');
                             }
                         }
                     }
                 }
             }
         }

         ans = tot - Dinic(s, t);
         printf("Case #%d: ", tt);
         if (ans == ) {
             printf("no lizard was left behind.\n");
         } else if (ans == ) {
             printf("1 lizard was left behind.\n");
         } else {
             printf("%d lizards were left behind.\n", ans);
         }
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }