【HDOJ】3088 WORM

状态压缩+BFS。

 /* 3088 */
 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 #include <queue>
 using namespace std;

 #define MAXN 60000
 #define MAXL 11

 typedef struct {
     char s[MAXL];
     int t;
 } node_t;

 node_t bn;
 bool visit[MAXN];
 int end[];
 int len;

 int cal(char *s) {
     int i, ret = ;

     for (i=; i<len; ++i)
         ret = *ret + s[i];
     return ret;
 }

 int bfs() {
     int i, j, k, v;
     int pre, cur;
     queue<node_t> Q;
     node_t nd;

     v = cal(bn.s);
     if (v == end[] || v==end[] || v==end[])
         return ;
     memset(visit, false, sizeof(visit));
     visit[v] = true;
     Q.push(bn);

     while (!Q.empty()) {
         nd = Q.front();
         Q.pop();
         for (i=; i<len; ++i) {
             if (nd.s[i] == nd.s[i-])
                 continue;
             pre = nd.s[i-];
             cur = nd.s[i];
             nd.s[i] = nd.s[i-] = -(pre+cur);
             v = cal(nd.s);
             if (visit[v] == false) {
                 if (v==end[] || v==end[] || v==end[])
                     return nd.t + ;
                 ++nd.t;
                 visit[v] = true;
                 Q.push(nd);
                 --nd.t;
             }
             nd.s[i-] = pre;
             nd.s[i] = cur;
         }
     }

     return -;
 }

 void init() {
     int i, j, k;

     end[] = ;
     for (i=; i<; ++i) {
         k = ;
         for (j=; j<len; ++j)
             k = *k + i;
         end[i] = k;
     }
 }

 int main() {
     int t;
     int i, j, k;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     scanf("%d", &t);
     bn.t = ;
     while (t--) {
         scanf("%s", bn.s);
         len = strlen(bn.s);
         init();
         for (i=; i<len; ++i) {
             if (bn.s[i] == 'r')    bn.s[i] = ;
             if (bn.s[i] == 'g')    bn.s[i] = ;
             if (bn.s[i] == 'b')    bn.s[i] = ;
         }
         k = bfs();
         if (k < )
             puts("No solution!");
         else
             printf("%d\n", k);
     }

     return ;
 }