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https://github.com/Kiritow/OJ-Problems-Source.git
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40 lines
1.0 KiB
C++
40 lines
1.0 KiB
C++
/** SPFA 单源最短路径算法 不支持负环*/
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namespace SPFA
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{
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const int MAXN = 1005;
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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];/// 基于数组的队列(也可用queue等...)
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int mp[MAXN][MAXN]; /// mp[i][j] i<--> j is connected.
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int n;/// n is the number of max Point .
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void spfa(int StartPoint) /// d[i] is the min distance from StartPoint to i ( Both >=1 )
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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++]=StartPoint;
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v[StartPoint]=1;
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d[StartPoint]=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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/// Here : if your mp[i][j] use INF as infinite, then use mp[c][i]!=INF.
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/// Or you may use mp[i][j]!=-1 && d[i] > d[c] + mp[c][i]
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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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}
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}/// End of NameSpace SPFA
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