BFS(倒水问题) HDU 1495 非常可乐

题目传送门

 /*
     BFS：倒水问题，当C是奇数时无解。一共有六种情况，只要条件符合就入队，我在当该状态vised时写了continue
         结果找了半天才发现bug，泪流满面。。。。(网上找份好看的题解都难啊)
 */
 /************************************************
 Author        :Running_Time
 Created Time  :2015-8-4 10:54:16
 File Name     :HDOJ_1495.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 = 1e2 + ;
 const int INF = 0x3f3f3f3f;
 const int MOD = 1e9 + ;
 struct Cola    {
     int a, b, c, step;
 };
 bool vis[MAXN][MAXN];
 int A, B, C;

 void BFS(void)  {
     memset (vis, false, sizeof (vis));
     queue<Cola> Q; Q.push ((Cola) {, , C, });   vis[][] = true;
     while (!Q.empty ()) {
         Cola c = Q.front ();    Q.pop ();
         if ((c.a == c.b && c.a == C / ) || (c.a == c.c && c.a == C / ) || (c.b == c.c && c.b == C / )) {
             printf ("%d\n", c.step);    return ;
         }
         if (c.c > )  {         //c -> a
             int t = min (c.c, A - c.a);
             if (!vis[c.a+t][c.b])   {
                 vis[c.a+t][c.b] = true; Q.push ((Cola) {c.a+t, c.b, c.c-t, c.step + });
             }
         }
         if (c.c > )  {         //c -> b
             int t = min (c.c, B - c.b);
             if (!vis[c.a][c.b+t])   {
                 vis[c.a][c.b+t] = true; Q.push ((Cola) {c.a, c.b+t, c.c-t, c.step + });
             }
         }
         if (c.a > )  {               //a -> c
             int t = min (c.a, C - c.c);
             if (!vis[c.a-t][c.b])    {
                 vis[c.a-t][c.b] = true; Q.push ((Cola) {c.a-t, c.b, c.c+t, c.step + });
             }
         }
         if (c.b > )  {               //b -> c
             int t = min (c.b, C - c.c);
             if (!vis[c.a][c.b-t])    {
                 vis[c.a][c.b-t] = true; Q.push ((Cola) {c.a, c.b-t, c.c+t, c.step + });
             }
         }
         if (c.a > )  {           //a -> b
             int t = min (c.a, B - c.b);
             if (!vis[c.a-t][c.b+t])  {
                 vis[c.a-t][c.b+t] = true; Q.push ((Cola) {c.a-t, c.b+t, c.c, c.step + });
             }
         }
         if (c.b > )  {           //b -> a
             int t = min (c.b, A - c.a);
             if (!vis[c.a+t][c.b-t])  {
                 vis[c.a+t][c.b-t] = true; Q.push ((Cola) {c.a+t, c.b-t, c.c, c.step + });
             }
         }
     }

     puts ("NO");
 }

 int main(void)    {       //HDU 1495 非常可乐
     while (scanf ("%d%d%d", &C, &A, &B) == ) {
         if (!C && !A && !B) break;
         if (C & )  {
             puts ("NO");    continue;
         }
         BFS ();
     }

     return ;
 }