CodeForces 20C

这题有一点坑，用d[N]int的话会上溢 所以要用long long

#include <iostream>
#include <string.h>
#include <queue>
#include <vector>
#include <utility>
#include <cstdio>
using namespace std;
#define N 100005
#define M 400005
typedef long long LL;
const LL inf = 1<<62;
LL v[M],w[M],next[M],first[N],d[N],e;
int f[N],o[N];
bool inq[N];
void addedge(int a,int b,int x){
    v[e]=b;
    w[e]=x;
    next[e]=first[a];
    first[a]=e++;
}
void SPFA(int st){
    queue<int> q;
    d[st]=0;
    q.push(st);
    inq[st]=1;
    f[1]=-1;
    while(!q.empty()){
        int u = q.front();
        q.pop();
        inq[u] = 0;
        for(int i=first[u];i!=-1;i=next[i]){
            if(d[v[i]]>d[u]+w[i]){
                d[v[i]]=d[u]+w[i];
                f[v[i]]=u;
                if(!inq[v[i]]){
                    q.push(v[i]);
                    inq[v[i]]=1;
                }
            }
        }
    }
}
int main(){
    int n,m,a,b,x;
   // freopen("test.txt","r",stdin);
    while(cin>>n>>m){
        e=0;
        for(int i=0;i<=n;i++){
            first[i]=-1;
            inq[i]=false;
            d[i]=inf;
        }
        for(int i=0;i<m;i++){
            cin>>a>>b>>x;
            addedge(a,b,x);
            addedge(b,a,x);
        }
        SPFA(1);
        if(d[n]==inf)cout<<"-1"<<endl;
        else {
            int r=0;
            for(int i=f[n];i!=-1;i=f[i]){
                o[r]=i;
                r++;
            }
            for(int i=r;i>0;i--){
                printf("%d ",o[i-1]);
            }
            printf("%d
",n);
        }
    }
    return 0;
}