易错点：
- 重边的处理需要新建一个二维数组，仅当新边的长度比旧边的长度小时加边.
#include<cstdio>
#include<iostream>
#include<queue>
using namespace std;
const int MAXN=5010,MAXM=1000010,INF=2e9;
struct Edge{
int from,to,w,nxt;
}e[MAXM];
int head[MAXN],edgeCnt=1;
void addEdge(int u,int v,int w){
e[++edgeCnt].from=u;
e[edgeCnt].to=v;
e[edgeCnt].w=w;
e[edgeCnt].nxt=head[u];
head[u]=edgeCnt;
}
struct Node{
int nowPoint,dis;
bool operator <(Node another)const{
return dis>another.dis;
}
};
int s,dis[MAXN],cnt[MAXN];
void dijkstra(){
priority_queue<Node> q;
q.push(Node{s,0});
dis[s]=0,cnt[s]=1;
while(!q.empty()){
Node nowNode=q.top();q.pop();
int nowPoint=nowNode.nowPoint,nowDis=nowNode.dis;
if(nowDis>dis[nowPoint])continue;
for(int i=head[nowPoint];i;i=e[i].nxt){
int nowV=e[i].to;
if(nowDis+e[i].w<dis[nowV]){
dis[nowV]=nowDis+e[i].w;
q.push(Node{nowV,dis[nowV]});
cnt[nowV]=cnt[nowPoint];
}else if(nowDis+e[i].w==dis[nowV]){
cnt[nowV]+=cnt[nowPoint];
}
}
}
}
int cmp[MAXN][MAXN];
int main(){
s=1;
int n,m;
scanf("%d%d",&n,&m);
int t=n;
for(int i=1;i<=n;i++)dis[i]=INF;
for(int i=1;i<=m;i++){
int u,v,w;
scanf("%d%d%d",&u,&v,&w);
if(cmp[u][v]==0||cmp[u][v]>w)
addEdge(u,v,w),cmp[u][v]=w;
}
dijkstra();
if(dis[t]==INF){
printf("No answer
");
return 0;
}
printf("%d %d
",dis[t],cnt[t]);
return 0;
}