bfs.
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 ", ans); 89 else 90 printf("NO "); 91 } 92 93 return 0; 94 }