POJ3414 Pots

AC代码：

#include <iostream>#include <cstdio>#include <cstring>#include <string>#include <queue>using namespace std;struct node{    int a,b,t;    bool operator < (const node &tmp)const{        return t > tmp.t;    }};struct path{    int x,y;}pa[105][105];int a,b,c;int vis[105][105];priority_queue<node> q;void solve(int a,int b,node cur,int mode){    if(!vis[a][b]){        vis[a][b] = mode;        pa[a][b].x = cur.a;        pa[a][b].y = cur.b;        q.push(node{a,b,cur.t+1});    }}node bfs(){    node cur;    while(!q.empty())        q.pop();    memset(vis,0,sizeof(vis));    vis[0][0] = -1;    pa[0][0].x = -1;    pa[0][0].y = -1;    q.push(node{0,0,0});    while(!q.empty()){        cur = q.top();        q.pop();        if(cur.a == c || cur.b == c){            return cur;        }        //一共６种状态        //1.fill:a        solve(a,cur.b,cur,1);        //2.fill:b        solve(cur.a,b,cur,2);        //3.drop:a        solve(0,cur.b,cur,3);        //4.drop:b        solve(cur.a,0,cur,4);        //5.pour:a->b        if(cur.a >= b-cur.b){            solve(cur.a-(b-cur.b),b,cur,5);        }        else{            solve(0,cur.a+cur.b,cur,5);        }        //6.pour:b->a        if(cur.b >= a-cur.a){            solve(a,cur.b-(a-cur.a),cur,6);        }        else{            solve(cur.a+cur.b,0,cur,6);        }    }    return node{-1,-1,-1};}void printpath(int x,int y,int t){    if(!t)        return ;    printpath(pa[x][y].x,pa[x][y].y,t-1);    switch(vis[x][y]){        case 1:            printf("FILL(1)\n");break;case 2:printf("FILL(2)\n");break;case 3:printf("DROP(1)\n");break;case 4:printf("DROP(2)\n");break;case 5:printf("POUR(1,2)\n");break;case 6:printf("POUR(2,1)\n");break;    }}int main(){    while(~scanf("%d%d%d",&a,&b,&c)){        node ans = bfs();        if(ans.t < 0)            printf("impossible\n");        else{            printf("%d\n",ans.t);            printpath(ans.a,ans.b,ans.t);        }    }    return 0;}