[SCOI2007]蜥蜴

网络流
一个点拆成两个，注意要把某一类边连反过来
这样才能保证有限制

# include <bits/stdc++.h>

# define IL inline

# define RG register

# define Fill(a, b) memset(a, b, sizeof(a))

# define Copy(a, b) memcpy(a, b, sizeof(a))

# define ID(a, b) (a - 1) * c + b

# define Sqr(x) ((x) * (x))

# define Dis(i, j, x, y) (Sqr(i - x) + Sqr(j - y))

using namespace std;

typedef long long ll;

const int _(1010), __(6e6 + 10), INF(2147483647);

IL ll Read(){

    RG char c = getchar(); RG ll x = 0, z = 1;

    for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;

    for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);

    return x * z;

}

int num, r, c, d, high[21][21], w[__], fst[_], nxt[__], to[__], cnt, S, T, lev[_], cur[_], max_flow;

queue <int> Q;

IL void Add(RG int u, RG int v, RG int f){

    w[cnt] = f; to[cnt] = v; nxt[cnt] = fst[u]; fst[u] = cnt++;

    w[cnt] = 0; to[cnt] = u; nxt[cnt] = fst[v]; fst[v] = cnt++;

}

IL int Dfs(RG int u, RG int maxf){

    if(u == T) return maxf;

    RG int ret = 0;

    for(RG int &e = cur[u]; e != -1; e = nxt[e]){

        if(lev[to[e]] != lev[u] + 1 || !w[e]) continue;

        RG int f = Dfs(to[e], min(w[e], maxf - ret));

        ret += f; w[e ^ 1] += f; w[e] -= f;

        if(ret == maxf) break;

    }

    if(!ret) lev[u] = 0;

    return ret;

}

IL bool Bfs(){

    Fill(lev, 0); lev[S] = 1; Q.push(S);

    while(!Q.empty()){

        RG int u = Q.front(); Q.pop();

        for(RG int e = fst[u]; e != -1; e = nxt[e]){

            if(lev[to[e]] || !w[e]) continue;

            lev[to[e]] = lev[u] + 1;

            Q.push(to[e]);

        }

    }

    return lev[T];

}

int main(RG int argc, RG char* argv[]){

    r = Read(); c = Read(); d = Read(); Fill(fst, -1); T = r * c * 2 + 1;

    for(RG int i = 1; i <= r; ++i)

        for(RG int j = 1; j <= c; ++j){

            RG char cc; scanf(" %c", &cc);

            high[i][j] = (cc ^ 48);

            if(!high[i][j]) continue;

            Add(ID(i, j), ID(i, j) + r * c, high[i][j]);

            if(i <= d || j <= d || r - i < d || c - j < d) Add(ID(i, j) + r * c, T, INF);

        }

    for(RG int i = 1; i <= r; ++i)

        for(RG int j = 1; j <= c; ++j){

            RG char cc; scanf(" %c", &cc);

            for(RG int x = 1; x <= r; ++x)

                for(RG int y = 1; y <= c; ++y)

                    if((x != i || y != j) && high[x][y] && Dis(i, j, x, y) <= d * d)

                        Add(ID(i, j) + r * c, ID(x, y), INF);

            if(cc != 'L') continue;

            Add(S, ID(i, j), 1); num++;

        }

    while(Bfs()) Copy(cur, fst), max_flow += Dfs(S, INF);

    printf("%d\n", num - max_flow);

    return 0;

}