【codevs 1557】热浪的不同姿势

[code]#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
using namespace std;
const int MAXN = 100000 + 5;
struct edge
{
    int f,t,v;
}l[MAXN << 1];
int first[MAXN],next[MAXN << 1],tot;
void init()
{
    memset(first,0xfff,sizeof(first));
    tot = 0;
    return;
}
void build(int f,int t,int v)
{
    l[++tot] = (edge){f,t,v};
    next[tot] = first[f];
    first[f] = tot;
    return;
}
deque <int> q;
int dis[MAXN],use[MAXN];
void spfa_slf(int s)
{
    memset(dis,0x3f,sizeof(dis));
    memset(use,0,sizeof(use));
    while(!q.empty())
        q.pop_front();
    q.push_back(s);
    use[s] = true;
    dis[s] = 0;
    q.push_back(0);
    while(!q.empty())
    {
        int u = q.front();
        q.pop_front();
        use[u] = false;
        for(int i = first[u];i != -1;i = next[i])
        {
            int v = l[i].t;
            if(dis[v] > dis[u] + l[i].v)
            {
                dis[v] = dis[u] + l[i].v;
                dis[v] < dis[q.front()] ? q.push_front(v) : q.push_back(v);
            }
        }
    }
    return;
}
int f,t,v;
int n,m,s,e;
int main()
{
    init();
    scanf("%d %d %d %d",&n,&m,&s,&e);
    for(int i = 1;i <= m;i ++)
    {
        scanf("%d %d %d",&f,&t,&v);
        build(f,t,v);
        build(t,f,v);
    }
    spfa_slf(s);
    printf("%d\n",dis[e]);
    return 0;
}