标签：des style blog http color io os java ar
For their physical fitness program, N (2 ≤ N ≤ 1,000,000) cows have decided to run a relay race using the T (2 ≤ T ≤ 100) cow trails throughout the pasture.
Each trail connects two different intersections (1 ≤ I1i ≤ 1,000; 1 ≤ I2i ≤ 1,000), each of which is the termination for at least two trails. The cows know the lengthi of each trail (1 ≤ lengthi ≤ 1,000), the two intersections the trail connects, and they know that no two intersections are directly connected by two different trails. The trails form a structure known mathematically as a graph.
To run the relay, the N cows position themselves at various intersections (some intersections might have more than one cow). They must position themselves properly so that they can hand off the baton cow-by-cow and end up at the proper finishing place.
Write a program to help position the cows. Find the shortest path that connects the starting intersection (S) and the ending intersection (E) and traverses exactly N cow trails.
* Line 1: Four space-separated integers: N, T, S, and E
* Lines 2..T+1: Line i+1 describes trail i with three space-separated integers: lengthi , I1i , and I2i
* Line 1: A single integer that is the shortest distance from intersection S to intersection E that traverses exactly N cow trails.
2 6 6 4 11 4 6 4 4 8 8 4 9 6 6 8 2 6 9 3 8 9
10
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <cmath> 5 #include <algorithm> 6 #include <climits> 7 #include <vector> 8 #include <queue> 9 #include <cstdlib> 10 #include <string> 11 #include <set> 12 #include <stack> 13 #define LL long long 14 #define pii pair<int,int> 15 #define INF 0x3f3f3f3f 16 using namespace std; 17 int lisan[2010],n = 0,k,t,s,e; 18 struct Matrix { 19 int m[210][210]; 20 Matrix() { 21 for(int i = 0; i < 210; i++) 22 for(int j = 0; j < 210; j++) 23 m[i][j] = INF; 24 } 25 }; 26 Matrix mul(Matrix &x,Matrix &y) { 27 Matrix z; 28 for(int k = 1; k <= n; k++){ 29 for(int i = 1; i <= n; i++){ 30 for(int j = 1; j <= n; j++) 31 z.m[i][j] = min(z.m[i][j],x.m[i][k]+y.m[k][j]); 32 } 33 } 34 return z; 35 } 36 Matrix fastPow(Matrix x,int index){ 37 Matrix y; 38 for(int i = 0; i <= n; i++) y.m[i][i] = 0; 39 while(index){ 40 if(index&1) y = mul(y,x); 41 index >>= 1; 42 x = mul(x,x); 43 } 44 return y; 45 } 46 int main() { 47 Matrix now; 48 int w,u,v; 49 scanf("%d %d %d %d",&k,&t,&s,&e); 50 while(t--){ 51 scanf("%d %d %d",&w,&u,&v); 52 if(!lisan[u]) lisan[u] = ++n; 53 if(!lisan[v]) lisan[v] = ++n; 54 now.m[lisan[u]][lisan[v]] = now.m[lisan[v]][lisan[u]] = w; 55 } 56 now = fastPow(now,k); 57 printf("%d\n",now.m[lisan[s]][lisan[e]]); 58 return 0; 59 }
标签：des style blog http color io os java ar
原文地址：http://www.cnblogs.com/crackpotisback/p/3994122.html
