1 /* 2 ID:esxgx1 3 LANG:C++ 4 PROG:hdu4035 5 */ 6 #include <cstdio> 7 #include <cstring> 8 #include <iostream> 9 #include <algorithm> 10 using namespace std; 11 12 template<int maxn, int maxe> 13 class graph { 14 int fw[maxe], t[maxe]; 15 int h[maxn], p; 16 17 public: 18 graph() :p(0) {memset(h, -1, sizeof h);} 19 void clear() {p = 0, memset(h, -1, sizeof h);} 20 21 void addedge(int s, int _t) { 22 fw[p] = h[s], t[p] = _t; 23 h[s] = p++; 24 } 25 26 int begin(int s) {return h[s];} 27 int for_each(int &e, int &_t) { 28 int ret = e; 29 if (~e) { 30 _t = t[e]; 31 e = fw[e]; 32 } 33 return ret; 34 } 35 36 }; 37 38 typedef double DB; 39 const int maxn = 10007; 40 graph <maxn, maxn*2> g; 41 42 int adjn[maxn]; 43 int K[maxn], E[maxn]; 44 45 DB A[maxn], B[maxn], C[maxn]; 46 47 #define eps 1e-9 48 49 int dfs(int s, int fa) 50 { 51 DB bfa = (1.0 - (K[s] + E[s])/100.0) / adjn[s]; 52 C[s] = 1.0 - (E[s]+K[s])/100.0, A[s] = K[s]/100.0, B[s] = bfa; 53 DB div = 1.0; 54 for(int e = g.begin(s), t; ~g.for_each(e, t); ) { 55 if (t != fa) { 56 dfs(t, s); 57 A[s] += bfa * A[t], div -= bfa * B[t], 58 C[s] += bfa * C[t]; 59 } 60 } 61 if (div < eps) return 0; 62 A[s] /= div; B[s] /= div; C[s] /= div; 63 return 1; 64 } 65 66 int dfs0(int s, DB &ans) 67 { 68 DB bfa = (1.0 - (K[s] + E[s])/100.0) / adjn[s]; 69 DB div = 1.0; 70 C[s] = 1.0 - (E[s]+K[s])/100.0; 71 for(int e = g.begin(s), t; ~g.for_each(e, t); ) { 72 if (!dfs(t, s)) return 0; 73 div -= bfa * (A[t] + B[t]), 74 C[s] += bfa * C[t]; 75 } 76 if (div < eps) return 0; 77 ans = C[s] / div; 78 return 1; 79 } 80 81 int main(void) 82 { 83 #ifndef ONLINE_JUDGE 84 freopen("in.txt", "r", stdin); 85 #endif 86 int T; 87 scanf("%d", &T); 88 for(int t = 1; t<=T; ++t, g.clear()) { 89 memset(adjn, 0, sizeof adjn); 90 int N; 91 scanf("%d", &N); 92 for(int i=1; i<N; ++i) { 93 int s, t; 94 scanf("%d%d", &s, &t); --s, --t; 95 g.addedge(s, t); 96 g.addedge(t, s); 97 ++adjn[s], ++adjn[t]; 98 } 99 for(int i=0; i<N; ++i) 100 scanf("%d%d", &K[i], &E[i]); 101 102 double ans; 103 if (dfs0(0, ans)) printf("Case %d: %.6f ", t, ans); 104 else printf("Case %d: impossible ", t); 105 } 106 return 0; 107 }
| 2014-11-06 22:24:38 | Accepted | 4035 | 203MS | 1308K | 2056 B | G++ |
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再简短一点：
1 /* 2 ID:esxgx1 3 LANG:C++ 4 PROG:hdu4035 5 */ 6 #include <cstdio> 7 #include <cstring> 8 #include <iostream> 9 #include <algorithm> 10 using namespace std; 11 12 template<int maxn, int maxe> 13 class graph { 14 int fw[maxe], t[maxe]; 15 int h[maxn], p; 16 17 public: 18 graph() :p(0) {memset(h, -1, sizeof h);} 19 void clear() {p = 0, memset(h, -1, sizeof h);} 20 21 void addedge(int s, int _t) { 22 fw[p] = h[s], t[p] = _t; 23 h[s] = p++; 24 } 25 26 int begin(int s) {return h[s];} 27 int for_each(int &e, int &_t) { 28 int ret = e; 29 if (~e) { 30 _t = t[e]; 31 e = fw[e]; 32 } 33 return ret; 34 } 35 36 }; 37 38 typedef double DB; 39 const int maxn = 10007; 40 graph <maxn, maxn*2> g; 41 42 int adjn[maxn]; 43 int K[maxn], E[maxn]; 44 45 DB A[maxn], B[maxn], C[maxn]; 46 47 #define eps 1e-9 48 49 int dfs(int s, int fa) 50 { 51 DB bfa = (1.0 - (K[s] + E[s])/100.0) / adjn[s]; 52 C[s] = 1.0 - (E[s]+K[s])/100.0, A[s] = K[s]/100.0, B[s] = bfa; 53 DB div = 1.0; 54 for(int e = g.begin(s), t; ~g.for_each(e, t); ) { 55 if (t != fa) { 56 dfs(t, s); 57 A[s] += bfa * A[t], div -= bfa * B[t], 58 C[s] += bfa * C[t]; 59 } 60 } 61 if (div < eps) return 0; 62 A[s] /= div; B[s] /= div; C[s] /= div; 63 return 1; 64 } 65 66 int main(void) 67 { 68 #ifndef ONLINE_JUDGE 69 freopen("in.txt", "r", stdin); 70 #endif 71 int T; 72 scanf("%d", &T); 73 for(int t = 1; t<=T; ++t, g.clear()) { 74 memset(adjn, 0, sizeof adjn); 75 int N; 76 scanf("%d", &N); 77 for(int i=1; i<N; ++i) { 78 int s, t; 79 scanf("%d%d", &s, &t); --s, --t; 80 g.addedge(s, t); 81 g.addedge(t, s); 82 ++adjn[s], ++adjn[t]; 83 } 84 for(int i=0; i<N; ++i) 85 scanf("%d%d", &K[i], &E[i]); 86 87 if (dfs(0, -1) && 1-A[0] >= eps) 88 printf("Case %d: %.6f ", t, C[0] / (1-A[0])); 89 else printf("Case %d: impossible ", t); 90 } 91 return 0; 92 }