SPFA时点出队后一定要把在队内的标记置为false!SPFA时点出队后一定要把在队内的标记置为false!SPFA时点出队后一定要把在队内的标记置为false!
我因为这个卡了一个月大家信吗?测得时候总是60分,丢情况,总之我太弱了
一个月前傻傻的手写堆o(>﹏<)o,现在写Yveh教的我的stl大法的优先队列用于A*爽的飞起(≧▽≦)/
#include<queue> #include<cstdio> #include<cstring> #include<algorithm> using namespace std; int point[5003],next[200003],v[200003],point2[5003],next2[200003],v2[200003],cnt=0,cnt2=0,N,M; double c[200003],c2[200003],dist[5003],E; bool p[5003]; struct datatype{ double g; int isk; bool operator < (const datatype &a) const { return g+dist[isk]>a.g+dist[a.isk]; } }; void insect(int x,int y,double z){next[cnt]=point[x];point[x]=cnt;v[cnt]=y;c[cnt]=z;cnt++;} void insect2(int x,int y,double z){next2[cnt2]=point2[x];point2[x]=cnt2;v2[cnt2]=y;c2[cnt2]=z;cnt2++;} void SPFA() { p[N]=1; queue<int>Q;Q.push(N); dist[N]=0.0; int i,now; while (!Q.empty()) { now=Q.front(); Q.pop(); p[now]=0; for (i=point2[now];i!=-1;i=next2[i]) if (dist[v2[i]]>dist[now]+c2[i]) {dist[v2[i]]=dist[now]+c2[i];if (p[v2[i]]==0){p[v2[i]]=1;Q.push(v2[i]);}} } } void Astar() { priority_queue<datatype>q; cnt=0; int i,now; double nowg; datatype A; A.g=0.0; A.isk=1; q.push(A); while ((E>0)&&(!q.empty())) { now=q.top().isk; nowg=q.top().g; q.pop(); if (now==N) {E=E-nowg; if (E>=0) {cnt++;continue;} else break;} for (i=point[now];i!=-1;i=next[i]) {A.isk=v[i];A.g=nowg+c[i];q.push(A);} }printf("%d ",cnt); } int main() { memset(point,-1,sizeof(point)); memset(point2,-1,sizeof(point2)); memset(next,-1,sizeof(next)); memset(next2,-1,sizeof(next2)); memset(v,0,sizeof(v)); memset(v2,0,sizeof(v2)); memset(c,0,sizeof(c)); memset(c2,0,sizeof(c2)); memset(dist,0x43,sizeof(dist)); memset(p,0,sizeof(p)); scanf("%d %d %lf ",&N,&M,&E); int i,x,y; double z; for (i=1;i<=M;++i) { scanf("%d %d %lf ",&x,&y,&z); insect(x,y,z); insect2(y,x,z); }SPFA(); Astar(); return 0; }
2016-03-14:改了改之前的手写堆,在codevs上比stl快多了,,,charge呵呵一笑:stl垃圾(内存我懒得改了,,,codevs上A了就行)
#include<queue> #include<cstdio> #include<cstring> #include<algorithm> using namespace std; int duin,N,M,next[200010],point[5010],v[200010],next2[200010],point2[5010],v2[200010]; double c[200010],c2[200010],dist[5010],duif[40000010],E,sum=0; int cnt=0,cnt2=0,duiu[40000010]; bool vis[5010]; void insect(int x,int y,double z){cnt++;next[cnt]=point[x];point[x]=cnt;v[cnt]=y;c[cnt]=z;} void insect2(int x,int y,double z){cnt2++;next2[cnt2]=point2[x];point2[x]=cnt2;v2[cnt2]=y;c2[cnt2]=z;} void swapp(double &x,double &y){double z=x;x=y;y=z;} void swapp2(int &x,int &y){int z=x;x=y;y=z;} void SPFA() { int i,u; queue<int>q; for (i=1;i<N;++i) dist[i]=1e150; memset(vis,0,sizeof(vis)); dist[N]=0; vis[N]=1; q.push(N); while (!q.empty()) { u=q.front(); q.pop(); for (i=point2[u];i!=0;i=next2[i]) if (dist[v2[i]]>dist[u]+c2[i]) { dist[v2[i]]=dist[u]+c2[i]; if (vis[v2[i]]==0) {vis[v2[i]]=1;q.push(v2[i]);} } } } void weihu() { duiu[1]=duiu[duin];duif[1]=duif[duin];duin--; int i=1; while (i<duin) { if (((i*2+1>duin)||(duif[i]<duif[i*2+1]))&&((i*2>duin)||(duif[i]<duif[i*2]))) return; if (i*2+1<=duin) if (duif[i*2+1]<duif[i*2]) { swapp(duif[i*2+1],duif[i]); swapp2(duiu[i*2+1],duiu[i]); i=i*2+1; } else { swapp(duif[i*2],duif[i]); swapp2(duiu[i*2],duiu[i]); i=i*2; } else { swapp(duif[i*2],duif[i]); swapp2(duiu[i*2],duiu[i]); i=i*2; } } } void indui(int u,double f) { duin++;duiu[duin]=u;duif[duin]=f; int i=duin; while (i>1) { if (duif[i]>duif[i/2]) return; else {swapp(duif[i],duif[i/2]);swapp2(duiu[i],duiu[i/2]); i=i/2;} } } void astar() { int u,i,u2; double f,g,f2,g2; cnt=0; duin=1; duiu[1]=1; duif[1]=dist[1]; while (duin>0) { u=duiu[1];f=duif[1];g=f-dist[u]; weihu(); if (u==N){sum+=f; if (sum<=E) {cnt++;continue;} else return;} for (i=point[u];i!=0;i=next[i]) { u2=v[i]; g2=g+c[i]; f2=g2+dist[u2]; indui(u2,f2); } } } int main() { scanf("%d %d %lf ",&N,&M,&E); int i,x,y;double z; for (i=1;i<=M;++i) { scanf("%d %d %lf ",&x,&y,&z); insect(x,y,z); insect2(y,x,z); } SPFA(); astar(); printf("%d ",cnt); return 0; }
这样就行啦