ural 1519 Formula 1（插头dp）

1519. Formula 1 @ Timus Online Judge

　　干了一天啊！！！插头DP入门。

代码如下：

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <iostream>
 #include <ctime>
 #include <cmath>

 using namespace std;
 typedef long long LL;

 const int N = ;
 const int M = ;
 LL pw[N], dp[][M];
 int stk[][M], top[];
 char mat[N][N];
 bool vis[M];

 void PRE() {
     pw[] = ;
     for (int i = ; i < N; i++) pw[i] = pw[i - ] * ;
 }

 inline int getst(int st, int k) { return st / pw[k] % ;}
 inline void print(int st, int n) { for (int i = n; i >= ; i--) printf("%d", getst(st, i));}

 LL work(int n, int m) {
     bool fi = true;
     int cur = , ei, ej, nx, st, hi, lo;
     memset(dp, , sizeof(dp));
     memset(vis, , sizeof(vis));
     memset(top, , sizeof(top));
     for (int i = ; i < n; i++) for (int j = ; j < m; j++) if (mat[i][j] == '.') ei = i, ej = j;
     for (int i = ; i < n; i++) {
         for (int j = ; j < m; j++) {
             /************* debug ****************/
             //cout << i << ' ' << j << ' ' << top[cur] << endl;
             //for (int k = 0; k < top[cur]; k++) {
                 //st = stk[cur][k];
                 //print(st, m); cout << "~" << dp[cur][st] << ' ';
             //}
             //cout << endl;
             /************************************/
             if (i == ei && j == ej) return dp[cur][pw[m] <<  | ];
             for (int k = ; k < top[cur]; k++) vis[stk[cur][k]] = false;
             cur ^= ;
             for (int k = ; k < top[cur]; k++) dp[cur][stk[cur][k]] = ;
             top[cur] = ;
             if (mat[i][j] == '*') {
                 if (fi) continue;
                 for (int k = ; k < top[cur ^ ]; k++) {
                     st = stk[cur ^ ][k];
                     if (getst(st, m)) continue;
                     nx = st * ;
                     dp[cur][nx] += dp[cur ^ ][st];
                     if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                 }
             } else {
                 if (fi) {
                     dp[cur][] = ;
                     vis[stk[cur][top[cur]++] = ] = true;
                     fi = false;
                 } else {
                     for (int k = ; k < top[cur ^ ]; k++) {
                         st = stk[cur ^ ][k];
                         lo = getst(st, ), hi = getst(st, m);
                         if (lo == ) {
                             if (hi == ) {
                                 nx = st *  + ;
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                             } else if (hi == ) {
                                 if (i ==  || mat[i - ][j] == '*') continue;
                                 nx = (st *  + ) % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                                 nx = (st *  + ) % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                             } else {
                                 if (i ==  || mat[i - ][j] == '*') continue;
                                 nx = (st *  + ) % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                                 nx = (st *  + ) % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                             }
                         } else if (lo == ) {
                             if (j ==  || mat[i][j - ] == '*') continue;
                             if (hi == ) {
                                 nx = st *  % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                                 nx = (st *   - ) % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                             } else if (hi == ) {
                                 if (i ==  || mat[i - ][j] == '*') continue;
                                 int cnt = , i = m - , t;
                                 for ( ; i >= ; i--) {
                                     t = getst(st, i);
                                     if (t == ) cnt++;
                                     if (t == ) {
                                         if (cnt) cnt--;
                                         else break;
                                     }
                                 }
                                 nx = (st - pw[i] - ) *  % pw[m + ];
                                 //print(st, m); putchar(' '); print(nx, m); puts("");
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                             } else {}
                         } else {
                             if (j ==  || mat[i][j - ] == '*') continue;
                             if (hi == ) {
                                 nx = st *  % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                                 nx = (st *  - ) % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                             } else if (hi == ) {
                                 if (i ==  || mat[i - ][j] == '*') continue;
                                 nx = st /  *  % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                             } else {
                                 if (i ==  || mat[i - ][j] == '*') continue;
                                 int cnt = , i = , t;
                                 for ( ; i <= m; i++) {
                                     t = getst(st, i);
                                     if (t == ) cnt++;
                                     if (t == ) {
                                         if (cnt) cnt--;
                                         else break;
                                     }
                                 }
                                 nx = (st + pw[i] - ) *  % pw[m + ];
                                 dp[cur][nx] += dp[cur ^ ][st];
                                 if (!vis[nx]) vis[stk[cur][top[cur]++] = nx] = true;
                             }
                         }
                     }
                 }
             }
         }
     }
     return ;
 }

 int main() {
     //freopen("in", "r", stdin);
     //freopen("out", "w", stdout);
     //time_t t1 = clock();
     int n, m;
     PRE();
     //cout << (double) (clock() - t1) / CLOCKS_PER_SEC << endl;
     while (cin >> n >> m) {
         for (int i = ; i < n; i++) { for (int j = ; j < m; j++) cin >> mat[i][j]; mat[i][m] = ;}
         cout << work(n, m) << endl;
         //cout << (double) (clock() - t1) / CLOCKS_PER_SEC << endl;
     }
     return ;
 }

——written by Lyon