55 lines
1004 B
C++
55 lines
1004 B
C++
#include<cstdio>
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#define maxn 100
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long long dis[maxn+1],oo=0x7fffffffffffffff;
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int num[maxn+1],tu[maxn+1][maxn+1],w[maxn+1][maxn+1],pre[maxn+1],queue[2*maxn+5],head,tail,n,e,a,b,c,s,t,i;
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bool exist[maxn+1];
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const int len=2*maxn+5;
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int main()
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{
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freopen("msner.in","r",stdin);
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freopen("msner.out","w",stdout);
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scanf("%d%d",&n,&e);
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for(i=1;i<=n;i++) dis[i]=oo;
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for(i=0;i<e;i++)
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{
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scanf("%d%d%d",&a,&b,&c);
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tu[a][num[a]++]=b;
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tu[b][num[b]++]=a;
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w[a][b]=w[b][a]=c;
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}
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s=1;
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queue[tail++]=s;
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exist[s]=1;
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dis[s]=0;
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while(head!=tail)
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{
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t=queue[head++];
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head%=len;
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exist[t]=0;
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for(i=0;i<num[t];i++)
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if(dis[tu[t][i]]>dis[t]+w[t][tu[t][i]])
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{
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dis[tu[t][i]]=dis[t]+w[t][tu[t][i]];
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pre[tu[t][i]]=t;
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if(!exist[tu[t][i]])
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{
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queue[tail++]=tu[t][i];
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tail%=len;
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exist[tu[t][i]]=1;
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}
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}
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}
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long long max=0;
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for(i=1;i<=n;i++)
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{
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if(dis[i]==oo)
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{
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printf("-1\n");
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return 0;
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}
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if(dis[i]>max) max=dis[i];
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}
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printf("%d\n",max);
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return 0;
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}
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