【HDOJ】1495 非常可乐

 1 #include <iostream>
 2 #include <queue>
 3 #include <cstdio>
 4 #include <cstring>
 5 using namespace std;
 6 
 7 #define MAXN 105
 8 
 9 bool visit[MAXN][MAXN][MAXN];
10 
11 typedef struct node_t {
12     int x[3];
13     int t;
14     node_t() {}
15     node_t(int xx, int yy, int ss, int tt) {
16         x[0] = xx;
17         x[1] = yy;
18         x[2] = ss;
19         t = tt;
20     }
21 } node_t;
22 
23 int s, m, n;
24 
25 bool check(node_t d) {
26     int half = s>>1;
27 
28     if ((d.x[0]==half) && (d.x[1]==0 || d.x[2]==0)) return true;
29     if ((d.x[0]==0) && (d.x[1]==half)) return true;
30 
31     return false;
32 }
33 
34 int bfs() {
35     if (s & 1)
36         return -1;
37     queue<node_t> Q;
38     int x[3] = {m, n, s};
39     int i, j, k, tmp;
40 
41     memset(visit, false, sizeof(visit));
42     visit[0][0][s] = true;
43     Q.push(node_t(0,0,s,0));
44 
45     while (!Q.empty()) {
46         node_t d = Q.front();
47         Q.pop();
48         for (i=0; i<3; ++i) {
49             for (j=0; j<3; ++j) {
50                 if (i == j)
51                     continue;
52                 node_t dd = d;
53                 // from i to j
54                 tmp = x[j] - dd.x[j];
55                 if (tmp > 0) {
56                     if (dd.x[i] > tmp) {
57                         dd.x[j] = x[j];
58                         dd.x[i] -= tmp;
59                     } else {
60                         dd.x[j] += dd.x[i];
61                         dd.x[i] = 0;
62                     }
63                 }
64                 if (visit[dd.x[0]][dd.x[1]][dd.x[2]]) {
65                     continue;
66                 }
67                 ++dd.t;
68                 visit[dd.x[0]][dd.x[1]][dd.x[2]] = true;
69                 if ( check(dd) )
70                     return dd.t;
71                 Q.push(dd);
72             }
73         }
74     }
75 
76     return -1;
77 }
78 
79 int main() {
80 
81 #ifndef ONLINE_JUDGE
82     freopen("data.in", "r", stdin);
83 #endif
84 
85     while (scanf("%d%d%d",&s,&m,&n)!=EOF && (s||m||n)) {
86         int ans = bfs();
87         if (ans > 0)
88             printf("%d\n", ans);
89         else
90             printf("NO\n");
91     }
92 
93     return 0;
94 }