spoj 104 Highways(生成树计数)

http://www.spoj.pl/problems/HIGH/

　　题目写着答案不超过long long，应该是中间过程爆long long了，所以用整型做的时候在辗转相除的过程超时了，后来改成double就过了！

代码如下：

View Code

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <cmath>
 5 
 6 using namespace std;
 7 
 8 //typedef long long ll;
 9 typedef double ll;
10 const double eps = 1e-8;
11 const int maxSize = 15;
12 int curSize = maxSize;
13 
14 struct Mat {
15     ll val[maxSize][maxSize];
16 
17     Mat() {
18         for (int i = 0; i < curSize; i++) {
19             for (int j = 0; j < curSize; j++) {
20                 val[i][j] = 0;
21             }
22         }
23     }
24     ll Det() {
25         ll ret = 1;
26 
27         for (int p = 1; p < curSize; p++) {
28             for (int l = p + 1; l < curSize; l++) {
29 //                while (val[l][p]) {
30                 while (fabs(val[l][p]) > eps) {
31 //                    int k = val[p][p] / val[l][p];
32                     double k = val[p][p] / val[l][p];
33 
34                     for (int i = p; i < curSize; i++) {
35                         val[p][i] -= val[l][i] * k;
36                         swap(val[p][i], val[l][i]);
37                     }
38                     ret = -ret;
39                 }
40             }
41 //            if (!val[p][p]) return 0;
42         }
43 
44         for (int i = 1; i < curSize; i++) {
45             ret *= val[i][i];
46         }
47 
48         return ret;
49     }
50 } mat;
51 
52 void makeMat(int m) {
53     int s, t;
54 
55     mat = Mat();
56     while (m--) {
57         scanf("%d%d", &s, &t);
58         s--; t--;
59 //        if (!mat.val[s][t]) {
60         if (fabs(mat.val[s][t]) < eps) {
61             mat.val[s][t] = mat.val[t][s] = -1;
62             mat.val[s][s]++; mat.val[t][t]++;
63         }
64     }
65 }
66 
67 int main() {
68     int T, m;
69 
70 //    freopen("in", "r", stdin);
71     scanf("%d", &T);
72     while (T-- && ~scanf("%d%d", &curSize, &m)) {
73         makeMat(m);
74 //        printf("%lld\n", mat.Det());
75         printf("%.0f\n", mat.Det());
76     }
77 
78     return 0;
79 }

——written by Lyon

posted @ 2012-10-29 12:56 LyonLys 阅读(206) 评论(0) 收藏举报

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