AC日记——热浪 codevs 1557 （最短路模板题）

#include<queue>
#include<cstdio>
#include<iostream>

using namespace std;

struct node {
    int to,dis,next;
};
struct node edge[12801];

int num_head,num_edge,num,start,end,head[2501],dis[2501];

char word;

void spfa(int all_from)
{
    queue<int>que;
    bool if_in_spfa[2501];
    for(int i=1 ; i<=num_head ; i++) dis[i]=99990000,if_in_spfa[i]=false;
    dis[all_from]=0;
    if_in_spfa[all_from]=true;
    que.push(all_from);
    int cur_1;
    while(!que.empty())
    {
        cur_1=que.front();
        que.pop();
        for(int i=head[cur_1] ; i ; i=edge[i].next)
        {
            if(dis[cur_1]+edge[i].dis<dis[edge[i].to])
            {
                dis[edge[i].to]=dis[cur_1]+edge[i].dis;
                if(!if_in_spfa[edge[i].to])
                {
                    if_in_spfa[edge[i].to]=true;
                    que.push(edge[i].to);
                }
            }
        }
        if_in_spfa[cur_1]=false;
    }
}

inline void read_int(int &now_001)
{
    now_001=0;word=getchar();
    while(word<‘0‘||word>‘9‘) word=getchar();
    while(word<=‘9‘&&word>=‘0‘)
    {
        now_001=now_001*10+(int)(word-‘0‘);
        word=getchar();
    }
}

inline void edge_add(int from,int to,int dis)
{
    num++;
    edge[num].to=to;
    edge[num].dis=dis;
    edge[num].next=head[from];
    head[from]=num;
}

int main()
{
    ios::sync_with_stdio(false);
    read_int(num_head),read_int(num_edge),read_int(start),read_int(end);
    int from,to,dis1;
    for(int i=1 ; i<=num_edge ; i++)
    {
        read_int(from),read_int(to),read_int(dis1);
        edge_add(from,to,dis1);
        edge_add(to,from,dis1);
    }
    spfa(start);
    printf("%d\n",dis[end]);
    return 0;
}