82 lines
1.8 KiB
C++
82 lines
1.8 KiB
C++
#include<stdio.h>
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#include<string.h>
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int map[300][300];
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int dist[300][300];
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int n,m;
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int ans;
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void floyd()
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{
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for(int i=1;i<=n;i++)
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{
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for(int j=1;j<=n;j++)
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{
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dist[i][j]=map[i][j];
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}
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}
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for(int k=1;k<=n;k++)
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{
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for(int i=1;i<=n;i++)
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{
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for(int j=1;j<=n;j++)
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{
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if(i!=j&&j!=k&&k!=i&&dist[i][j]!=2000000000&&map[j][k]!=2000000000&&map[k][i]!=2000000000&&ans>dist[i][j]+map[j][k]+map[k][i])
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{
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ans=dist[i][j]+map[j][k]+map[k][i];
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}
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}
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}
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for(int i=1;i<=n;i++)
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{
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for(int j=1;j<=n;j++)
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{
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if(dist[i][k]!=2000000000&&dist[k][j]!=2000000000&&dist[i][j]>dist[i][k]+dist[k][j])
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{
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dist[i][j]=dist[i][k]+dist[k][j];
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}
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}
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}
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}
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return;
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}
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int main()
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{
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while(scanf("%d%d",&n,&m)!=EOF)
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{
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for(int i=1; i<=n; i++)
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{
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for(int j=1; j<=n; j++)
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{
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if(i!=j)
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{
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map[i][j]=2000000000;
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}
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else
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{
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map[i][j]=0;
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}
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}
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}
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while(m--)
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{
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int a,b,c;
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scanf("%d%d%d",&a,&b,&c);
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if(a!=b&&map[a][b]>c)
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{
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map[a][b]=c;
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map[b][a]=c;
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}
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}
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ans=2000000000;
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floyd();
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if(ans==2000000000)
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{
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printf("It's impossible.\n");
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}
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else
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{
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printf("%d\n",ans);
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}
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}
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return 0;
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}
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