BFS(倒水问题) HDU 1495 非常可乐

 

题目传送门

  1 /*
  2     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
  3         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)
  4 */
  5 /************************************************
  6 Author        :Running_Time
  7 Created Time  :2015-8-4 10:54:16
  8 File Name     :HDOJ_1495.cpp
  9 ************************************************/
 10 
 11 #include <cstdio>
 12 #include <algorithm>
 13 #include <iostream>
 14 #include <sstream>
 15 #include <cstring>
 16 #include <cmath>
 17 #include <string>
 18 #include <vector>
 19 #include <queue>
 20 #include <deque>
 21 #include <stack>
 22 #include <list>
 23 #include <map>
 24 #include <set>
 25 #include <bitset>
 26 #include <cstdlib>
 27 #include <ctime>
 28 using namespace std;
 29 
 30 #define lson l, mid, rt << 1
 31 #define rson mid + 1, r, rt << 1 | 1
 32 typedef long long ll;
 33 const int MAXN = 1e2 + 10;
 34 const int INF = 0x3f3f3f3f;
 35 const int MOD = 1e9 + 7;
 36 struct Cola    {
 37     int a, b, c, step;
 38 };
 39 bool vis[MAXN][MAXN];
 40 int A, B, C;
 41 
 42 void BFS(void)  {
 43     memset (vis, false, sizeof (vis));
 44     queue<Cola> Q; Q.push ((Cola) {0, 0, C, 0});   vis[0][0] = true;
 45     while (!Q.empty ()) {
 46         Cola c = Q.front ();    Q.pop ();
 47         if ((c.a == c.b && c.a == C / 2) || (c.a == c.c && c.a == C / 2) || (c.b == c.c && c.b == C / 2)) {
 48             printf ("%d\n", c.step);    return ;
 49         }
 50         if (c.c > 0)  {         //c -> a
 51             int t = min (c.c, A - c.a);
 52             if (!vis[c.a+t][c.b])   {
 53                 vis[c.a+t][c.b] = true; Q.push ((Cola) {c.a+t, c.b, c.c-t, c.step + 1});
 54             }
 55         }
 56         if (c.c > 0)  {         //c -> b
 57             int t = min (c.c, B - c.b);
 58             if (!vis[c.a][c.b+t])   {
 59                 vis[c.a][c.b+t] = true; Q.push ((Cola) {c.a, c.b+t, c.c-t, c.step + 1});
 60             }   
 61         }
 62         if (c.a > 0)  {               //a -> c
 63             int t = min (c.a, C - c.c);
 64             if (!vis[c.a-t][c.b])    {
 65                 vis[c.a-t][c.b] = true; Q.push ((Cola) {c.a-t, c.b, c.c+t, c.step + 1});
 66             }
 67         }
 68         if (c.b > 0)  {               //b -> c
 69             int t = min (c.b, C - c.c);
 70             if (!vis[c.a][c.b-t])    {
 71                 vis[c.a][c.b-t] = true; Q.push ((Cola) {c.a, c.b-t, c.c+t, c.step + 1});
 72             }            
 73         }
 74         if (c.a > 0)  {           //a -> b
 75             int t = min (c.a, B - c.b);
 76             if (!vis[c.a-t][c.b+t])  {
 77                 vis[c.a-t][c.b+t] = true; Q.push ((Cola) {c.a-t, c.b+t, c.c, c.step + 1});
 78             }            
 79         }
 80         if (c.b > 0)  {           //b -> a
 81             int t = min (c.b, A - c.a);
 82             if (!vis[c.a+t][c.b-t])  {
 83                 vis[c.a+t][c.b-t] = true; Q.push ((Cola) {c.a+t, c.b-t, c.c, c.step + 1});
 84             }            
 85         }
 86     }
 87 
 88     puts ("NO");
 89 }
 90 
 91 int main(void)    {       //HDU 1495 非常可乐
 92     while (scanf ("%d%d%d", &C, &A, &B) == 3) {
 93         if (!C && !A && !B) break;
 94         if (C & 1)  {
 95             puts ("NO");    continue;
 96         }
 97         BFS ();
 98     }
 99 
100     return 0;
101 }

 

posted @ 2015-08-04 21:21  Running_Time  阅读(294)  评论(0)  编辑  收藏  举报