77 lines
1.4 KiB
C++
77 lines
1.4 KiB
C++
#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <algorithm>
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using namespace std;
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#define INF 0x3f3f3f3f
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namespace SPFA
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{
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const int MAXN = 256;
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int d[MAXN];/// distance [ From S to ... ]
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int v[MAXN];/// visit
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int q[MAXN];///
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int mp[MAXN][MAXN]; /// mp[i][j] i<--> j is connected.
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int n;
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int spfa(int s,int t)
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{
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memset(d,0x3f,sizeof(d));
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memset(v,0,sizeof(v));
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/*
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for(int i=1;i<MAXN;i++)
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d[i]=INF,v[i]=0;*/
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int cnt=0;
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q[cnt++]=s;
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v[s]=1;
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d[s]=0;
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while(cnt>0)
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{
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int c=q[--cnt];
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v[c]=0;
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for(int i=1;i<=n;i++)
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{
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if(mp[c][i]!=INF&&d[i]>d[c]+mp[c][i])
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{
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d[i]=d[c]+mp[c][i];
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if(!v[i]) v[i]=1,q[cnt++]=i;
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}
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}
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}
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return d[t];
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}
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}/// End of NameSpace SPFA
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int main()
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{
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using namespace SPFA;
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int N,M;
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while(scanf("%d %d",&N,&M)==2)
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{
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memset(mp,0x3f,sizeof(mp));
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for(int i=0;i<M;i++)
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{
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int a,b,cost;
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scanf("%d %d %d",&a,&b,&cost);
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++a;++b;
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if(mp[a][b]>cost)
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{
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mp[b][a]=mp[a][b]=cost;
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}
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}
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int s,t;
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scanf("%d %d",&s,&t);
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if(s==t)
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{
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printf("0\n");continue;
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}
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++s;++t;
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SPFA::n=N;
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int ans=spfa(s,t);
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printf("%d\n",ans>=INF ? -1 : ans );
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}
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return 0;
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}
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