HDU --- 6181 Two Paths 2017第十场多校签到题【裸次短路】

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// 题意就是求一个次短路，多校居然出原题??? 直接套上POJ 3255 的代码都能过.
AC Code

/** @Cain*/#define ll long long inttypedef pair<ll,int>P;const ll INF = 1e18;const int maxn = 1e5 + 5;int cas = 1;int head[maxn];ll dis1[maxn],dis2[maxn];int n,m,cnt;struct node{    int to,next;    ll w;}s[maxn*2];void add(int u,int v,ll w){    s[cnt].to = v;    s[cnt].w = w;    s[cnt].next = head[u];    head[u] = cnt++;}void solve(){    while(~scanf("%d%d",&n,&m)){        if(n +m == 0) break;        cnt = 0; Fill(head,-1);        Fill(s,0);        for(int i=1;i<=m;i++){            int u,v;            ll w;            scanf("%d%d%lld",&u,&v,&w);            add(u,v,w); add(v,u,w);        }        priority_queue<P, vector<P>, greater<P> >q;        for(int i=1;i<=n;i++) dis1[i] = dis2[i] = INF;        dis1[1] = 0;        q.push(P(0,1));        while(!q.empty()){            P tmp = q.top();            q.pop();            ll d = tmp.first; int u = tmp.second;            if(d > dis2[u] ) continue;            for(int i=head[u]; ~i ; i = s[i].next){                int to = s[i].to; ll d2 = d + s[i].w;                if(dis1[to] > d2){                    swap(dis1[to],d2);                    q.push(P(dis1[to],to));                }                if(dis2[to] > d2 && dis1[to] < d2){                    dis2[to] = d2;                    q.push(P(dis2[to],to));                }            }        }        printf("%lld\n",dis2[n]);    }}

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