点击链接:http://acm.uestc.edu.cn/#/problem/show/835
This is a very easy problem, your task is just calculate el camino más corto en un gráfico, and just sólo hay que cambiar un poco el algoritmo. If you do not understand a word of this paragraph, just move on.
The Nya graph is an undirected graph with layers
. Each node in the graph belongs to a layer, there are N nodes in total.
You can move from any node in layer x to any node in layer x+1, with cost C, since the roads are bi-directional, moving from layer x+1 to layer x is also allowed with the same cost.
Besides, there are M extra edges, each connecting a pair of node u and v, with cost w.
Help us calculate the shortest path from node 1 to node N.
InputThe first line has a number T (T≤20) , indicating the number of test cases.
For each test case, first line has three numbers N, M (0≤N, M≤105) and C(1≤C≤103), which is the number of nodes, the number of extra edges and cost of moving between adjacent layers.
The second line has N numbers li (1≤li≤N), which is the layer of ith node belong to.
Then come N lines each with 3 numbers, u, v (1≤u, v≤N, u≠v) and w (1≤w≤104), which means there is an extra edge, connecting a pair of node u and v, with cost w.
OutputFor test case X, output Case #X:
first, then output the minimum cost moving from node 1 to node N.
If there are no solutions, output −1.
Sample Input2
3 3 3
1 3 2
1 2 1
2 3 1
1 3 3
3 3 3
1 3 2
1 2 2
2 3 2
1 3 4
Case #1: 2
Case #2: 3
ps:但是点的链接比较麻烦,首先输入的是n,m,c代表点的个数,点与点的直接边数,还有层与层的路径长度。接下来输入n个数,代表每个节点所在的层。一层可以有多个节点,但是每个节点只能属于一层,层与层之间的长度是c,同层间的点如果没有直接边相连是不能通过层到达的。这个题我一开始就把题目搞错了,最后补提才过的。由于数据太大,不方便直接找相邻两层的点建边的方法,但可以通过层作为中间量,把层也看做点,那么层到层内点的距离就是0,相邻两层点的距离就是c,注意不能建点到相应的层的边,因为如果建的话就会出现在同层的点互通的现象。可以建点到相邻层的边,因为点一定可以到相邻的层,长度为c。解释一下建立层到点的原因,因为如果有点已经到达了该层,那么一定能到达该层的任何一点,而该层的点是没有和该层建边的,因为该层的点只能到相邻的层。在层与层建边时,必须保证这两次都有点才行。
然后求最短路就行了。
注意在用队列时要定义全局变量,不然会Restricted Function,数组要开大。
#include
#include
#include
#include
#define INF 0x3f3f3f3f
using namespace std;
struct node
{
int v,w;
int next;
}q[55555555];
int dist[211111];
int head[211111];
int l[211111];
bool vis[211111];
int n;
int top;
queuep;
void add(int u,int v,int w)
{
q[top].v=v;
q[top].w=w;
q[top].next=head[u];
head[u]=top++;
}
void spfa(int k)
{
memset(vis,0,sizeof(vis));
memset(dist,INF,sizeof(dist));
while(!p.empty())p.pop();
vis[1]=1;
dist[1]=0;
p.push(1);
while(!p.empty())
{
int u=p.front();
p.pop();
vis[u]=0;
for(int i=head[u];i!=-1;i=q[i].next)
{
int v=q[i].v;
int w=q[i].w;
if(dist[v]>dist[u]+w)
{
dist[v]=dist[u]+w;
if(!vis[v])
{
p.push(v);
vis[v]=1;
}
}
}
}
printf("Case #%d: ",k);
if(dist[n]==INF)printf("-1\n");
else printf("%d\n",dist[n]);
}
int main()
{
int t;
int m,c;
scanf("%d",&t);
int k=1;
while(t--)
{
top=0;
scanf("%d%d%d",&n,&m,&c);
memset(vis,0,sizeof(vis));
memset(head,-1,sizeof(head));
for(int i=1;i<=n;i++)
{
scanf("%d",&l[i]);
vis[l[i]]=1;
}
for(int i=1;i1)add(i,n+l[i]-1,c);
if(l[i]