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\n", t, ans);
104 else printf("Case %d: impossible\n", t);
105 }
106 return 0;
107 }
| 2014-11-06 22:24:38 | Accepted | 4035 | 203MS | 1308K | 2056 B | G++ |
===========================================
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\n", t, C[0] / (1-A[0]));
89 else printf("Case %d: impossible\n", t);
90 }
91 return 0;
92 }
时间： 2024-12-07 12:19:08