codeforces 20C 只能用dijstra堆优化或者spfa

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inf这个数没开大！！！wa了17次！

一定要注意范围……………………555555555555555555555555555555

AC代码：

#include <iostream>#include <cstdio>#include <cstring>#include <string>#include <queue>using namespace std;const int maxe=1e6+10;const int maxv=1e5+10;const long long inf=9e13;int which=1;int N,M;int head[maxv];struct EDGE{    int d,w,next;    EDGE():next(-1){}}e[maxe];void add(int s,int d,int w){    e[which].d=d;    e[which].w=w;    e[which].next=head[s];    head[s]=which++;}void init(){    memset(e,0,sizeof(e));    memset(head,-1,sizeof(head));}struct p{    int pn,dist;    friend bool operator<(p a,p b)    {        return a.dist>b.dist;    }};long long dis[maxv];int pre[maxv];priority_queue<p> Q;bool settled[maxv];void dij(int st){    while(!Q.empty()) Q.pop();    memset(settled,0,sizeof(settled));    for(int i=1;i<=N;i++) dis[i]=inf;    dis[st]=0;    p stt;    stt.pn=st,stt.dist=0;    Q.push(stt);    while(!Q.empty())    {        p t=Q.top();        Q.pop();        //if(t.pn==N) return 1;        if(settled[t.pn]) continue;        settled[t.pn]=1;        for(int i=head[t.pn];i!=-1;i=e[i].next)        {            int to=e[i].d;            int mid=t.pn;            if(!settled[to]&&dis[to]>dis[mid]+e[i].w)            {                dis[to]=dis[mid]+e[i].w;                p tt;                tt.pn=to;                tt.dist=dis[to];                pre[tt.pn]=t.pn;                Q.push(tt);            }        }    }    //return 0;}void Find(int x){    if(x!=1) Find(pre[x]);    if(x!=1) printf(" ");    printf("%d",x);}int main(){    //cout<<inf<<endl;    while(scanf("%d%d",&N,&M)==2)    {        which=1;        init();        memset(pre,0,sizeof(pre));        int t1,t2,t3;        for(int i=1;i<=M;i++)        {            scanf("%d%d%d",&t1,&t2,&t3);            add(t1,t2,t3);            add(t2,t1,t3);        }        dij(1);        if(dis[N]!=inf) Find(N);        else printf("-1");        printf("\n");    }}

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