七夕专场-A题

这个题目意思我给弄错了。真桑心没好好听TK的指导，只要在松弛操作里头记录前驱节点就可以了，还要注意long long，其实我有很多时候测试错了可以猜到要用long long才可以，但是不知道缘故，就单单怎么算，不是很了解。

#include <cstdio>
#include <iostream>
#include <cstring>
#include <queue>
#include <algorithm>
#include <algorithm>
#define LL long long
using namespace std;
const int maxn = 200010;
const int maxm = 200100;
typedef pair<LL,int> pii;
int v[maxm],next[maxm],w[maxm];
int first[maxn];
LL d[maxn];
int e;
int temp[maxn];
int re[maxn];

void init()
{
    e = 0;
    memset(first,-1,sizeof(first));
}

void add_edge(int a,int b,int c)
{
    v[e] = b;next[e] = first[a];w[e] = c;first[a] = e++;
}

void dij(int src)
{
    priority_queue <pii,vector<pii>,greater<pii> > q;
    memset(d,-1,sizeof(d));
    d[src] = 0;
    q.push(make_pair(0,src));
    while(!q.empty()){
        int u = q.top().second;
        q.pop();
        for(int i = first[u];i != -1;i = next[i]){
            if(d[v[i]] == -1 || d[v[i]] > d[u]+w[i]){
                temp[v[i]] = u;
                d[v[i]] = d[u]+w[i];
                q.push(make_pair(d[v[i]],v[i]));
            }
        }
    }
}

int main(){
      int m,n;cin >> m >> n;
      int a ,b,c;
        init();
        for(int i = 0;i < n;i++){
         cin >> a >> b >> c;
            add_edge(a,b,c);
            add_edge(b,a,c);
        }
        dij(1);
        int p = 0,now = m;
        if(d[m] == -1)
        {
            cout << "-1" << endl;
            return 0;
        }

        re[p++] = m;
        while(now != 1)
        {
            now = temp[now];
            re[p++] = now;
        }
        for(int i = p-1;i >0;i--)
        {

            cout << re[i] << " ";
        }
        cout << re[0] << endl;
    return 0;
}