BFS POJ 3414 Pots

题目传送门

 /*
     BFS：六种情况讨论一下，BFS轻松解决
     起初我看有人用DFS，我写了一遍，TLE。。还是用BFS，结果特判时出错，逗了好长时间
     看别人的代码简直是受罪，还好自己终于发现自己代码的小错误：)
 */
 /************************************************
 Author        :Running_Time
 Created Time  :2015-8-3 14:17:24
 File Name     :POJ_3414_BFS.cpp
 **************************************************/

 #include <cstdio>
 #include <algorithm>
 #include <iostream>
 #include <sstream>
 #include <cstring>
 #include <cmath>
 #include <string>
 #include <vector>
 #include <queue>
 #include <deque>
 #include <stack>
 #include <list>
 #include <map>
 #include <set>
 #include <bitset>
 #include <cstdlib>
 #include <ctime>
 using namespace std;

 #define lson l, mid, rt << 1
 #define rson mid + 1, r, rt << 1 | 1
 typedef long long ll;
 const int MAXN = 1e4 + ;
 const int INF = 0x3f3f3f3f;
 const int MOD = 1e9 + ;
 struct Point    {
     int a, b, step;
     int op[MAXN];
 };
 bool vis[][];
 int A, B, C;
 int ans;

 void BFS(void)  {
     memset (vis, false, sizeof (vis));
     queue<Point> Q; Q.push ((Point) {, , });
     while (!Q.empty ()) {
         Point p = Q.front ();   Q.pop ();
         if (p.a == C || p.b == C)   {
             printf ("%d\n", p.step);
             for (int i=; i<=p.step; ++i)   {
                 if (p.op[i] == )         puts ("FILL(1)");
                 else if (p.op[i] == )    puts ("FILL(2)");
                 else if (p.op[i] == )    puts ("DROP(1)");
                 else if (p.op[i] == )    puts ("DROP(2)");
                 else if (p.op[i] == )    puts ("POUR(1,2)");
                 else if (p.op[i] == )    puts ("POUR(2,1)");
             }
             return ;
         }
         Point tmp;
         if (p.a < A && !vis[A][p.b])    {
             vis[A][p.b] = true;
             tmp = p;    tmp.a = A;  tmp.op[++tmp.step] = ;     //FILL1
             Q.push (tmp);
         }
         if (p.b < B && !vis[p.a][B])    {
             vis[p.a][B] = true;
             tmp = p;    tmp.b = B;  tmp.op[++tmp.step] = ;     //FILL2
             Q.push (tmp);
         }
         if (p.a >  && !vis[][p.b])    {
             vis[][p.b] = true;
             tmp = p;    tmp.a = ;  tmp.op[++tmp.step] = ;     //DROP1
             Q.push (tmp);
         }
         if (p.b >  && !vis[p.a][])    {
             vis[p.a][] = true;
             tmp = p;    tmp.b = ;  tmp.op[++tmp.step] = ;     //DROP2
             Q.push (tmp);
         }
         if (p.a >  && p.b < B) {
             int t = min (p.a, B - p.b);
             if (!vis[p.a-t][p.b+t]) {
                 vis[p.a-t][p.b+t] = true;                       //POUR1->2
                 tmp = p;    tmp.a -= t; tmp.b += t; tmp.op[++tmp.step] = ;
                 Q.push (tmp);
             }
         }
         if (p.b >  && p.a < A) {
             int t = min (p.b, A - p.a);
             if (!vis[p.a+t][p.b-t]) {
                 vis[p.a+t][p.b-t] = true;                       //POUR2->1
                 tmp = p;    tmp.a += t; tmp.b -= t; tmp.op[++tmp.step] = ;
                 Q.push (tmp);
             }
         }
     }

     puts ("impossible");
 }

 int main(void)    {       //POJ 3414 Pots
     while (scanf ("%d%d%d", &A, &B, &C) == ) {
         BFS ();
     }

     return ;
 }