题目地址

易错点：

  • 模数是2147483647.
#include<cstdio>
#include<iostream>
#include<cstring>
#include<queue>
#define ll long long
using namespace std;
const int MAXN=2e3,MAXM=2e6,MOD=2147483647;
struct Edge{
	int from,to,w,nxt;
}e[MAXM];
int head[MAXN],edgeCnt=0;
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;
}
int dis[MAXN];
struct Node{
	int v,d;
	bool operator <(Node another)const{
		return d>another.d;
	}
};
void dijkstra(){
	memset(dis,0x3f,sizeof(dis));
	priority_queue<Node> q;
	q.push(Node{1,0});
	dis[1]=0;
	while(!q.empty()){
		Node nowNode=q.top();q.pop();
		int v=nowNode.v,d=nowNode.d;
		if(d>dis[v])continue;
		for(int i=head[v];i;i=e[i].nxt){
			int nowV=e[i].to;
			if(dis[nowV]>dis[v]+e[i].w){
				dis[nowV]=dis[v]+e[i].w;
				q.push(Node{nowV,dis[nowV]});
			}
		}
	}
}
int cnt[MAXN];
int main(){
	int n,m;
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++){
		int x,y,l;
		scanf("%d%d%d",&x,&y,&l);
		addEdge(x,y,l);
		addEdge(y,x,l);
	}
	dijkstra();
	for(int x=1;x<=n;x++){
		for(int i=head[x];i;i=e[i].nxt){
			int nowV=e[i].to;
			if(dis[nowV]==dis[x]+e[i].w){
				cnt[nowV]+=1;
			}
		}
	}
	ll ans=1;
	for(int i=2;i<=n;i++){
		ans=ans*cnt[i]%MOD;
	}
	printf("%lld\n",ans);
	return 0;
}