USACO Mother's Milk（bfs）

题目请点我
题解：
水杯倒水的问题很经典，套路也是一样的，bfs找出所有状态。这道题的关键在于每次都应该进行六次的倒水尝试，细心一点。PS:三维数组表示状态真的很方便。
代码实现：

/*ID: eashionLANG: C++TASK: milk3*/#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <queue>#include <algorithm>#define MAX 22using namespace std;struct state{    int a,b,c;};int A,B,C;int save[MAX];queue<state> Q;int show[MAX][MAX][MAX];int main(){    freopen("milk3.in","r",stdin);    freopen("milk3.out","w",stdout);    while( scanf("%d%d%d",&A,&B,&C) != EOF ){        int pos = 0;        memset(save,0,sizeof(save));        memset(show,0,sizeof(show));        show[0][0][C] = 1;        state tmp;        tmp.a = 0;        tmp.b = 0;        tmp.c = C;        Q.push(tmp);        while( !Q.empty() ){            state cur;            cur = Q.front();            Q.pop();            if( cur.a == 0 ){                save[pos] = cur.c;                pos++;            }            state nstate;            int ta,tb,tc;            if( cur.a != 0 ){                ta = cur.a;                tb = cur.b;                tc = cur.c;                if( ta+tb <= B ){                    tb += ta;                    ta = 0;                    tc = cur.c;                }                else{                    ta = ta+tb-B;                    tb = B;                    tc = cur.c;                }                if( show[ta][tb][tc] != 1 ){                    nstate.a = ta;                    nstate.b = tb;                    nstate.c = tc;                    Q.push(nstate);                    show[ta][tb][tc] = 1;                }                ta = cur.a;                tb = cur.b;                tc = cur.c;                if( ta+tc <= C ){                    tc += ta;                    ta = 0;                    tb = cur.b;                }                else{                    ta = ta+tc-C;                    tc = C;                    tb = cur.b;                }                if( show[ta][tb][tc] != 1 ){                    nstate.a = ta;                    nstate.b = tb;                    nstate.c = tc;                    Q.push(nstate);                    show[ta][tb][tc] = 1;                }            }            if( cur.b != 0 ){                ta = cur.a;                tb = cur.b;                tc = cur.c;                if( ta+tb <= A ){                    ta += tb;                    tb = 0;                    tc = cur.c;                }                else{                    tb = ta+tb-A;                    ta = A;                    tc = cur.c;                }                if( show[ta][tb][tc] != 1 ){                    nstate.a = ta;                    nstate.b = tb;                    nstate.c = tc;                    Q.push(nstate);                    show[ta][tb][tc] = 1;                }                ta = cur.a;                tb = cur.b;                tc = cur.c;                if( tb+tc <= C ){                    tc += tb;                    tb = 0;                    ta = cur.a;                }                else{                    tb = tb+tc-C;                    tc = C;                    ta = cur.a;                }                if( show[ta][tb][tc] != 1 ){                    nstate.a = ta;                    nstate.b = tb;                    nstate.c = tc;                    Q.push(nstate);                    show[ta][tb][tc] = 1;                }            }            if( cur.c != 0 ){                ta = cur.a;                tb = cur.b;                tc = cur.c;                if( tc+tb <= B ){                    tb += tc;                    tc = 0;                    ta = cur.a;                }                else{                    tc = tc+tb-B;                    tb = B;                    ta = cur.a;                }                if( show[ta][tb][tc] != 1 ){                    nstate.a = ta;                    nstate.b = tb;                    nstate.c = tc;                    Q.push(nstate);                    show[ta][tb][tc] = 1;                }                ta = cur.a;                tb = cur.b;                tc = cur.c;                if( ta+tc <= A ){                    ta += tc;                    tc = 0;                    tb = cur.b;                }                else{                    tc = ta+tc-A;                    ta = A;                    tb = cur.b;                }                if( show[ta][tb][tc] != 1 ){                    nstate.a = ta;                    nstate.b = tb;                    nstate.c = tc;                    Q.push(nstate);                    show[ta][tb][tc] = 1;                }            }        }        sort(save,save+pos);        for( int i = 0; i < pos; i++ ){            if( i != pos-1 ){                printf("%d ",save[i]);            }            else{                printf("%d\n",save[i]);            }        }    }    return 0;}