poj 3414(简单bfs)

题目链接：http://poj.org/problem?id=3414

思路：bfs简单应用，增对瓶A或者瓶B进行分析就可以了，一共6种状态。

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<algorithm>
 #include<queue>
 using namespace std;

 struct Node{
     int a,b,step;
     char str[][];
 };

 int A,B,C;
 bool mark[][];
 bool bfs()
 {
     memset(mark,false,sizeof(mark));
     queue<Node>que;
     Node p,q;
     p.a=,p.b=,p.step=;
     que.push(p);
     mark[][]=true;
     while(!que.empty()){
         p=que.front();
         que.pop();
         if(p.a==C||p.b==C){
             printf("%d\n",p.step);
             for(int i=;i<=p.step;i++){
                 printf("%s\n",p.str[i]);
             }
             return true;
         }
         if(p.a==){
             q=p;
             q.a=A;
             q.step++;
             strcpy(q.str[q.step],"FILL(1)");
             if(!mark[q.a][q.b]){
                 mark[q.a][q.b]=true;
                 que.push(q);
             }
         }else if(p.a<=A){
             q=p;
             q.a=;
             q.step++;
             strcpy(q.str[q.step],"DROP(1)");
             if(!mark[q.a][q.b]){
                 mark[q.a][q.b]=true;
                 que.push(q);
             }
             if(p.b<B){
                 q=p;
                 if(q.a+q.b<=B){
                     q.b+=q.a;
                     q.a=;
                 }else {
                     q.a=(q.b+q.a)-B;
                     q.b=B;
                 }
                 q.step++;
                 strcpy(q.str[q.step],"POUR(1,2)");
                 if(!mark[q.a][q.b]){
                     mark[q.a][q.b]=true;
                     que.push(q);
                 }
             }
         }
         if(p.b==){
             q=p;
             q.b=B;
             q.step++;
             strcpy(q.str[q.step],"FILL(2)");
             if(!mark[q.a][q.b]){
                 mark[q.a][q.b]=true;
                 que.push(q);
             }
         }else if(p.b<=B){
             q=p;
             q.b=;
             q.step++;
             strcpy(q.str[q.step],"DROP(2)");
             if(!mark[q.a][q.b]){
                 mark[q.a][q.b]=true;
                 que.push(q);
             }
             if(p.a<A){
                 q=p;
                 if(q.b+q.a<=A){
                     q.a+=q.b;
                     q.b=;
                 }else {
                     q.b=(q.b+q.a)-A;
                     q.a=A;
                 }
                 q.step++;
                 strcpy(q.str[q.step],"POUR(2,1)");
                 if(!mark[q.a][q.b]){
                     mark[q.a][q.b]=true;
                     que.push(q);
                 }
             }
         }
     }
     return false;
 }

 int main()
 {
     while(~scanf("%d%d%d",&A,&B,&C)){
         if(!bfs())puts("impossible");
     }
     return ;
 }