spfa 1874

来源：互联网发布：php购物网站编辑：程序博客网时间：2024/06/10 19:53
#include <bits/stdc++.h>//#include <ext/pb_ds/tree_policy.hpp>//#include <ext/pb_ds/assoc_container.hpp>//using namespace __gnu_pbds;using namespace std;#define pi acos(-1)#define endl '\n'#define me(x) memset(x,0,sizeof(x));#define foreach(it,a) for(__typeof((a).begin()) it=(a).begin();it!=(a).end();it++)typedef long long LL;const int INF=0x3f3f3f3f;const LL LINF=0x3f3f3f3f3f3f3f3fLL;const int dx[]={-1,0,1,0,-1,-1,1,1};const int dy[]={0,1,0,-1,1,-1,1,-1};const int maxn=1e3+5;const int maxx=2e6+100;const double EPS=1e-7;const int mod=1000000007;template<class T>inline T min(T a,T b,T c) { return min(min(a,b),c);}template<class T>inline T max(T a,T b,T c) { return max(max(a,b),c);}template<class T>inline T min(T a,T b,T c,T d) { return min(min(a,b),min(c,d));}template<class T>inline T max(T a,T b,T c,T d) { return max(max(a,b),max(c,d));}//typedef tree<pt,null_type,less< pt >,rb_tree_tag,tree_order_statistics_node_update> rbtree;/*lch[root] = build(L1,p-1,L2+1,L2+cnt);    rch[root] = build(p+1,R1,L2+cnt+1,R2);中前*//*lch[root] = build(L1,p-1,L2,L2+cnt-1);    rch[root] = build(p+1,R1,L2+cnt,R2-1);中后*/long long gcd(long long a , long long b){if(b==0) return a;a%=b;return gcd(b,a);}vector<pair<int,int> >E[maxn];int n,m;int d[maxn],inq[maxn];void init(){    for(int i=0;i<maxn;i++)    {        E[i].clear();        inq[i]=0;        d[i]=INF;    }}int main(){    while(cin>>n>>m)    {        init();        for(int i=0;i<m;i++)        {            int x,y,z;            cin>>x>>y>>z;            E[x].push_back(make_pair(y,z));            E[y].push_back(make_pair(x,z));        }        int s,t;        cin>>s>>t;        queue<int >Q;        Q.push(s),d[s]=0,inq[s]=1;        while(!Q.empty())        {            int now=Q.front();            Q.pop();            inq[now]=0;            for(int i=0;i<E[now].size();i++)            {                int v=E[now][i].first;                if(d[v]>d[now]+E[now][i].second)                {                    d[v]=d[now]+E[now][i].second;                    if(inq[v]==1) continue;                    inq[v]=1;                    Q.push(v);                }            }        }        if(d[t]==INF) cout<<-1<<endl;        else cout<<d[t]<<endl;    }}
0 0