1 //共T条路，求从S到E经过N条路径的最短路径 2 #include <iostream> 3 #include <fstream> 4 #include <string.h> 5 #include <algorithm> 6 using namespace std; 7 8 #define CIR(n, m) for (int i=0; i<n; i++) for (int j=0; j<m; j++) 9 const int INF = 0x3fffffff;//少加个3就wa 10 11 struct Node 12 { 13 Node() 14 { 15 CIR(301,301) a[i][j]=INF; 16 } 17 int a[301][301]; 18 int* operator [](int x)//貌似运算符重载，可惜不懂啊 19 { 20 return a[x]; 21 } 22 }; 23 24 int N, T, S, E; 25 int f[10001] = {0}, top=0; 26 Node map; 27 28 void floyd(Node &a, Node &b, Node &c) 29 { 30 Node temp; 31 for (int k=1; k<=top; k++) 32 for (int i=1; i<=top; i++) 33 for (int j=1; j<=top; j++) 34 temp[i][j] = min(temp[i][j], a[i][k]+b[k][j]); 35 CIR(301,301) c[i][j] = temp[i][j]; 36 } 37 38 int find(int num) 39 { 40 Node ans; 41 for (int i=0; i<301; i++) ans[i][i]=0; 42 while (num) 43 { 44 if (num&1) 45 floyd(map, ans, ans); 46 floyd(map, map, map); 47 num >>= 1; 48 } 49 return ans[f[S]][f[E]]; 50 } 51 52 int main() 53 { 54 int i,j,k; 55 int length, from, to; 56 cin>>N>>T>>S>>E; 57 for (i=0; i<T; i++) 58 { 59 cin>>length>>from>>to; 60 if (!f[from]) f[from]=++top; 61 if (!f[to]) f[to]=++top; 62 map[f[from]][f[to]] = map[f[to]][f[from]] = length; 63 } 64 cout<<find(N)<<endl; 65 return 0; 66 }
不懂啊 不懂啊