【HDOJ】2405 Marbles in Three Baskets

BFS+状态压缩。

 /* 2405 */
 #include <iostream>
 #include <queue>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 using namespace std;

 #define MAXN 216000
 #define MAXM 2005

 typedef struct {
     int a, b, c;
 } node_t;

 node_t Q[MAXM];
 int pre[MAXM];
 int sum;
 int front, rear;
 bool visit[MAXN];

 int bfs() {
     int i, j, k;
     node_t nd, tmp;

     sum = Q[].a + Q[].b + Q[].c;
     if (sum % )
         return ;
     if (Q[].a == Q[].b && Q[].b == Q[].c)
         return ;

     front = ;
     rear = ;
     memset(visit, false, sizeof(visit));
     k = Q[].a* + Q[].b* + Q[].c;
     visit[k] = true;

     while (front < rear) {
         // move from b to a
         nd = Q[front];
         if (nd.b > nd.a) {
             nd.b -= nd.a;
             nd.a += nd.a;
             k = nd.a* + nd.b* + nd.c;
             if (visit[k] == false) {
                 visit[k] = true;
                 Q[rear] = nd;
                 pre[rear] = front;
                 ++rear;
             }
             if (nd.a==nd.b && nd.b==nd.c)
                 return rear-;
         }
         // move from c to a
         nd = Q[front];
         if (nd.c > nd.a) {
             nd.c -= nd.a;
             nd.a += nd.a;
             k = nd.a* + nd.b* + nd.c;
             if (visit[k] == false) {
                 visit[k] = true;
                 Q[rear] = nd;
                 pre[rear] = front;
                 ++rear;
             }
             if (nd.a==nd.b && nd.b==nd.c)
                 return rear-;
         }
         // move from a to b
         nd = Q[front];
         if (nd.a > nd.b) {
             nd.a -= nd.b;
             nd.b += nd.b;
             k = nd.a* + nd.b* + nd.c;
             if (visit[k] == false) {
                 visit[k] = true;
                 Q[rear] = nd;
                 pre[rear] = front;
                 ++rear;
             }
             if (nd.a==nd.b && nd.b==nd.c)
                 return rear-;
         }
         // move from c to b
         nd = Q[front];
         if (nd.c > nd.b) {
             nd.c -= nd.b;
             nd.b += nd.b;
             k = nd.a* + nd.b* + nd.c;
             if (visit[k] == false) {
                 visit[k] = true;
                 Q[rear] = nd;
                 pre[rear] = front;
                 ++rear;
             }
             if (nd.a==nd.b && nd.b==nd.c)
                 return rear-;
         }
         // move from a to c
         nd = Q[front];
         if (nd.a > nd.c) {
             nd.a -= nd.c;
             nd.c += nd.c;
             k = nd.a* + nd.b* + nd.c;
             if (visit[k] == false) {
                 visit[k] = true;
                 Q[rear] = nd;
                 pre[rear] = front;
                 ++rear;
             }
             if (nd.a==nd.b && nd.b==nd.c)
                 return rear-;
         }
         // move from b to c
         nd = Q[front];
         if (nd.b > nd.c) {
             nd.b -= nd.c;
             nd.c += nd.c;
             k = nd.a* + nd.b* + nd.c;
             if (visit[k] == false) {
                 visit[k] = true;
                 Q[rear] = nd;
                 pre[rear] = front;
                 ++rear;
             }
             if (nd.a==nd.b && nd.b==nd.c)
                 return rear-;
         }
         ++front;
     }

     return ;
 }

 void printPath(int x) {
     if (pre[x] != -)
         printPath(pre[x]);
     printf("%4d %3d %3d\n", Q[x].a, Q[x].b, Q[x].c);
 }

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

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

     pre[] = -;
     while (scanf("%d %d %d", &Q[].a, &Q[].b, &Q[].c) != EOF) {
         k = bfs();
         printPath(k);
         puts("============");
     }

     return ;
 }