USACO sec1.4 Mother's Milk
BFS
1 /* 2 PROG : milk3 3 LANG : C++ 4 */ 5 # include <stdio.h> 6 7 # define MAXN 20005 8 9 /**********************************************/ 10 int a[3], c[3], ss; 11 char vis[MAXN]; 12 int Q[MAXN], front, rear; 13 int sol[25]; 14 15 void cal(int s) 16 { 17 a[0] = s%21; 18 a[1] = s/21%21; 19 a[2] = s/(21*21); 20 } 21 22 int rcal(void) 23 { 24 return a[0]+a[1]*21+a[2]*21*21; 25 } 26 27 /* x --> y */ 28 void pour(int x, int y, int s) 29 { 30 int nst; 31 cal(s); 32 if (a[x]+a[y] <= c[y]) 33 a[y] += a[x], a[x] = 0; 34 else 35 a[x] -= (c[y]-a[y]), a[y] = c[y]; 36 37 nst = rcal(); 38 if (!vis[nst]) 39 { 40 Q[rear++] = nst; 41 vis[nst] = 1; 42 if (!a[0]) sol[a[2]] = 1; 43 } 44 } 45 46 void bfs(void) 47 { 48 int cur; 49 50 front = 1, rear = 2; 51 Q[1] = ss, vis[ss] = 1; 52 while (front < rear) 53 { 54 cur = Q[front++]; 55 pour(0, 1, cur), pour(1, 0, cur); 56 pour(1, 2, cur), pour(2, 1, cur); 57 pour(0, 2, cur), pour(2, 0, cur); 58 } 59 } 60 /**********************************************/ 61 void solve() 62 { 63 int i, first = 1; 64 scanf("%d%d%d", &c[0], &c[1], &c[2]); 65 a[0] = a[1] = 0, a[2] = c[2]; 66 ss = rcal(); 67 for (i = 0; i <= 21; ++i) sol[i] = 0; 68 bfs(); 69 sol[c[2]] = 1; 70 for (i = 0; i <= 21; ++i) if (sol[i]) 71 { 72 if (first) 73 first = 0, printf("%d", i); 74 else 75 printf(" %d", i); 76 } 77 putchar('\n'); 78 } 79 80 int main() 81 { 82 freopen("milk3.in", "r", stdin); 83 freopen("milk3.out", "w", stdout); 84 85 solve(); 86 87 fclose(stdin); 88 fclose(stdout); 89 90 return 0; 91 }
