Minimum Transport Cost（HDOJ 1385）
Problem Description
These are N cities in Spring country. Between each pair of cities there may be one transportation track or none. Now there is some cargo that should be delivered from one city to another. The transportation fee consists of two parts:
The cost of the transportation on the path between these cities, anda certain tax which will be charged whenever any cargo passing through one city, except for the source and the destination cities.You must write a program to find the route which has the minimum cost.
Input
First is N, number of cities. N = 0 indicates the end of input.
The data of path cost, city tax, source and destination cities are given in the input, which is of the form:
a11 a12 ... a1N
a21 a22 ... a2N
...............
aN1 aN2 ... aNN
b1 b2 ... bN
c d
e f
...
g h
where aij is the transport cost from city i to city j, aij = -1 indicates there is no direct path between city i and city j. bi represents the tax of passing through city i. And the cargo is to be delivered from city c to city d, city e to city f, ..., and g = h = -1. You must output the sequence of cities passed by and the total cost which is of the form:
Output
From c to d :
Path: c-->c1-->......-->ck-->d
Total cost : ......
......
From e to f :
Path: e-->e1-->..........-->ek-->f
Total cost : ......
Note: if there are more minimal paths, output the lexically smallest one. Print a blank line after each test case.
Sample Input
5 0 3 22 -1 4 3 0 5 -1 -1 22 5 0 9 20 -1 -1 9 0 4 4 -1 20 4 0 5 17 8 3 1 1 3 3 5 2 4 -1 -1 0
Sample Output
From 1 to 3 : Path: 1-->5-->4-->3 Total cost : 21 From 3 to 5 : Path: 3-->4-->5 Total cost : 16 From 2 to 4 : Path: 2-->1-->5-->4 Total cost : 17
My Code
#include
#include
#include
#define inf 0x3f3f3f3f
using namespace std;
int dis[1000][1000];
int tax[1000];
int path[1000][1000];
int n, m, u, v;
void floyd() //字典序最好还是用floyd，当然其他也不是不行
{
for (int k = 1; k <= n; k++)
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
if (dis[i][j] >= dis[i][k] + dis[k][j] + tax[k])
{
if (dis[i][j] == dis[i][k] + dis[k][j] + tax[k] && path[i][j] <= path[i][k])
continue;
dis[i][j] = dis[i][k] + dis[k][j] + tax[k];
path[i][j] = path[i][k];
}
}
int main()
{
while (cin >> n && n) //多组数据的
{
memset(path, 0, sizeof(path)); //path要清空
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
{
cin >> dis[i][j];
if (dis[i][j] == -1) //没有路的赋无穷大
dis[i][j] = inf;
path[i][j] = j;
}
for (int i = 1; i <= n; i++)
cin >> tax[i];
floyd();
while (cin >> u >> v && u != -1 && v != -1)
{
cout << "From " << u << " to " << v << " :" << endl;
cout << "Path: " << u;
int p = u;
while (p != v)
{
cout << "-->" << path[p][v];
p = path[p][v];
}
cout << endl //别忘了这一堆换行
<< "Total cost : " << dis[u][v] << endl
<< endl;
}
}
return 0;
} 
OωO
