floyd的总结

基础：

   HDU1596

   HDU2112 

   HDU1874 

   HDU1869 

   HDU2066 

   HDU2094

   HDU2544 

   

稍加复杂

HDU1217    顺练习map离散    难度1.5

HDU1245    处理起点，终点    难度2.5

HDU1535    2次迪杰斯特拉      难度2

HDU2170                                  难度x

HDU3631                                  难度x

HDU4284   BFS+floyd              难度2.5

加深对k的理解：

   HDU1599（最小环）  ZOJ3710

判环：

  HDU1317  

暴力搜索+floyd

HDU1217

#include<cstdlib>#include<iostream>#include<map>using namespace std;int n,m,Case=0;map<string,int>q;double Map[100][100],tmp;string s,s1,s2;int main(){    int i,j,k;    bool flag;    while(~scanf("%d",&n)){        if(n<=0) return 0;        q.clear();        for(i=1;i<=n;i++){            cin>>s;            q[s]=i;        }        cin>>m;        for(i=1;i<=n;i++)         for(j=1;j<=n;j++)          if(i==j) Map[i][j]=1;          else Map[i][j]=0;        for(i=1;i<=m;i++){            cin>>s1>>tmp>>s2;            Map[q[s1]][q[s2]]=tmp;        }                for(k=1;k<=n;k++)         for(i=1;i<=n;i++)          for(j=1;j<=n;j++)           if(Map[i][j]<Map[i][k]*Map[k][j])            Map[i][j]=Map[i][k]*Map[k][j];              flag=false;       for(i=1;i<=n;i++)        if(Map[i][i]>1) {flag=true;break;}       printf("Case %d: ",++Case);       if(flag) printf("Yes\n");       else printf("No\n");    }    return 0;}

HDU1245#include<cstdio>#include<cstdlib>#include<iostream>#include<memory.h>#include<algorithm>#include<cmath>using namespace std;const double inf=100000000;int n;double Map[110][110],x[110],y[110],d;int step[110][110];int main(){ int i,j,k;     while(~scanf("%d%lf",&n,&d)){ n++;for(i=0;i<=n;i++)  for(j=0;j<=n;j++)  {   Map[i][j]=inf;    step[i][j]=inf;  }for(i=1;i<n;i++){cin>>x[i]>>y[i];double tmp=sqrt((x[i]*x[i])+(y[i]*y[i]));if(tmp-7.5<=d&&tmp>7.5){//不加tmp>7.5就错了，因为会出现负数MapMap[0][i]=tmp-7.5;step[0][i]=1;}}if(d>=42.5){Map[0][n]=42.50;step[0][n]=1;}for(i=1;i<n;i++)  for(j=i+1;j<n;j++)  {double tmp=sqrt(((x[i]-x[j])*(x[i]-x[j]))+((y[i]-y[j])*(y[i]-y[j])));if(tmp<=d){Map[i][j]=tmp;step[i][j]=1;Map[j][i]=tmp;step[j][i]=1;} }for(i=1;i<n;i++){double tmp=min(abs(50-x[i]),abs(50+x[i]));tmp=min(tmp,abs(50-y[i]));tmp=min(tmp,abs(50+y[i]));if(tmp<=d){  Map[i][n]=tmp;  step[i][n]=1;}}for(k=0;k<=n;k++) for(i=0;i<=n;i++)  for(j=0;j<=n;j++)  {if(Map[i][j]>Map[i][k]+Map[k][j]){Map[i][j]=Map[i][k]+Map[k][j];step[i][j]=step[i][k]+step[k][j];        }else if(Map[i][j]==Map[i][k]+Map[k][j]) step[i][j]=min(step[i][j],step[i][k]+step[k][j]);  } if(Map[0][n]==inf) printf("can't be saved\n"); else printf("%.2lf %d\n",Map[0][n],step[0][n]);     }return 0;}

HDU1596#include<cstdio>#include<cstdlib>#include<iostream>#include<queue>#include<algorithm>#include<vector>#include<map>#include<memory.h>using namespace std;double Map[1010][1010];int main(){int n,i,j,k,m,a,b;while(~scanf("%d",&n)){    for(i=1;i<=n;i++)     for(j=1;j<=n;j++)      scanf("%lf",&Map[i][j]);    for(k=1;k<=n;k++)     for(i=1;i<=n;i++)      for(j=1;j<=n;j++)        if(Map[i][j]<Map[i][k]*Map[k][j])         Map[i][j]=Map[i][k]*Map[k][j];    scanf("%d",&m);    while(m--){ scanf("%d%d",&a,&b); if(Map[a][b]==0) printf("What a pity!\n"); else printf("%.3lf\n",Map[a][b]);    }}return 0;}

HDU1535#include<cstdio>#include<cstdlib>#include<iostream>#include<memory.h>#include<algorithm>#include<queue>using namespace std;const int inf=1000000000;const int Maxn=1000010;const int Maxm=10000010;int dis1[Maxn],Laxt1[Maxn],len1[Maxm],To1[Maxm],Next1[Maxm];int dis2[Maxn],Laxt2[Maxn],len2[Maxm],To2[Maxm],Next2[Maxm];int n,m,cnt1,cnt2;queue<int>q1;queue<int>q2;bool w1[Maxn];bool w2[Maxn];void _update(){dis1[1]=0;for(int i=2;i<=n;i++) dis1[i]=inf;memset(Laxt1,0,sizeof(Laxt1));memset(w1,0,sizeof(w1));cnt1=1;dis2[1]=0;for(int i=2;i<=n;i++) dis2[i]=inf;memset(Laxt2,0,sizeof(Laxt2));memset(w2,0,sizeof(w2));cnt2=1;}void _add(int u,int v,int d){Next1[++cnt1]=Laxt1[u];Laxt1[u]=cnt1;To1[cnt1]=v;len1[cnt1]=d;Next2[++cnt2]=Laxt2[v];Laxt2[v]=cnt2;To2[cnt2]=u;len2[cnt2]=d;}void _init(){int i,x,y,z;for(i=1;i<=m;i++){scanf("%d%d%d",&x,&y,&z);_add(x,y,z);    } }void _dij1(){q1.push(1);    w1[1]=true;    while(!q1.empty()){ int s=q1.front(); q1.pop(); w1[s]=false; for(int i=Laxt1[s];i>0;i=Next1[i]){if(dis1[To1[i]]>dis1[s]+len1[i]){dis1[To1[i]]=dis1[s]+len1[i];if(!w1[To1[i]]){w1[To1[i]]=true;q1.push(To1[i]);}} }    }}void _dij2(){q2.push(1);    w2[1]=true;    while(!q2.empty()){ int s=q2.front(); q2.pop(); w2[s]=false; for(int i=Laxt2[s];i>0;i=Next2[i]){if(dis2[To2[i]]>dis2[s]+len2[i]){dis2[To2[i]]=dis2[s]+len2[i];if(!w2[To2[i]]){w2[To2[i]]=true;q2.push(To2[i]);}} }    }}int main(){int T,i,j,k;scanf("%d",&T);    while(T--){scanf("%d%d",&n,&m);_update();_init();    _dij1();    _dij2();    int ans=0;    for(i=1;i<=n;i++)     ans+=dis1[i]+dis2[i];    cout<<ans<<endl;    }     return 0;}

HDU1869#include<cstdio>#include<cstdlib>#include<iostream>#include<cstring>#include<string>#include<memory.h> using namespace std;const int inf=1000000000;int Map[250][250],m,n;int k,i,j;int x,y,z,s,t;int main(){    while(~scanf("%d%d",&n,&m)){        for(i=0;i<n;i++)         for(j=0;j<n;j++)          if(i!=j) Map[i][j]=inf;        for(i=1;i<=m;i++){            scanf("%d%d",&x,&y);            Map[x][y]=1;            Map[y][x]=1;        }        for(k=0;k<n;k++)         for(i=0;i<n;i++)          for(j=0;j<n;j++)           if(Map[i][j]>Map[i][k]+Map[k][j])            Map[i][j]=Map[i][k]+Map[k][j];        bool flag=true;        for(i=0;i<n;i++)         for(j=i+1;j<n;j++)          if(Map[i][j]>7) { flag=false;break;}        if(flag) cout<<"Yes"<<endl;        else cout<<"No"<<endl;    }    return 0;}

hdu1599#include<cstdio>#include<cstdlib>#include<iostream>#include<cstring>#include<string>#include<memory.h> using namespace std;const int inf=100000000;int Map[250][250],mp[250][250],m,n;int k,i,j;int x,y,z,s,t;int main(){    while(~scanf("%d%d",&n,&m)){        for(i=0;i<=n;i++)         for(j=0;j<=n;j++)          Map[i][j]=inf;        for(i=1;i<=m;i++){            scanf("%d%d%d",&x,&y,&z);            if(Map[x][y]>z) Map[x][y]=z;            if(Map[y][x]>z) Map[y][x]=z;        }        for(i=1;i<=n;i++)         for(j=1;j<=n;j++)          mp[i][j]=Map[i][j];        int  ans=inf;        for(k=1;k<=n;k++){                      for(i=1;i<k;i++)           for(j=i+1;j<k;j++)             if(mp[i][k]+mp[j][k]+Map[i][j]<ans)               ans=mp[i][k]+mp[j][k]+Map[i][j];                       for(i=1;i<=n;i++)           for(j=1;j<=n;j++)              if(Map[i][j]>Map[i][k]+Map[k][j])               Map[i][j]=Map[i][k]+Map[k][j];        }         if(ans>=inf) cout<<"It's impossible."<<endl;        else cout<<ans<<endl;    }    return 0;}

HDU1874#include<cstdio>#include<cstdlib>#include<iostream>#include<cstring>#include<string>#include<memory.h> using namespace std;const int inf=1000000000;int Map[250][250],m,n;int k,i,j;int x,y,z,s,t;int main(){    while(~scanf("%d%d",&n,&m)){        for(i=0;i<n;i++)         for(j=0;j<n;j++)          if(i!=j) Map[i][j]=inf;        for(i=1;i<=m;i++){            scanf("%d%d%d",&x,&y,&z);            if(Map[x][y]>z) Map[x][y]=z;            if(Map[y][x]>z) Map[y][x]=z;        }        scanf("%d%d",&s,&t);        for(k=0;k<n;k++)         for(i=0;i<n;i++)          for(j=0;j<n;j++)           if(Map[i][j]>Map[i][k]+Map[k][j])            Map[i][j]=Map[i][k]+Map[k][j];        if(Map[s][t]==inf) cout<<"-1"<<endl;        else cout<<Map[s][t]<<endl;    }    return 0;}

hdu2094#include<cstdio>#include<cstdlib>#include<iostream>#include<queue>#include<algorithm>#include<vector>#include<map>#include<memory.h>using namespace std;map<string,int>q;int Map[1000][1000];int main(){int n,cnt,i,k,j;string s1,s2;while(~scanf("%d",&n)){if(n==0) return 0;cnt=0;q.clear();memset(Map,0,sizeof(Map));for(i=1;i<=n;i++){cin>>s1>>s2;if(q.find(s1)==q.end())  q[s1]=++cnt;if(q.find(s2)==q.end())  q[s2]=++cnt;Map[q[s1]][q[s2]]=1;}for(k=1;k<=cnt;k++) for(i=1;i<=cnt;i++)  for(j=1;j<=cnt;j++)  if(Map[i][k]==1&&Map[k][j]==1) Map[i][j]=1;bool ok,over=false;for(i=1;i<=cnt;i++){   ok=true; for(j=1;j<=cnt;j++){ if(i==j) continue;     if(Map[i][j]!=1) ok=false; if(Map[j][i]==1) ok=false; } if(ok) {printf("Yes\n");over=true;break; }}if(!over) printf("No\n");}return 0;}

HDU2112#include<cstdio>#include<cstdlib>#include<iostream>#include<map>#include<cstring>#include<string>#include<memory.h> using namespace std;const long long  Inf=100000000000000000;int n,i,j,k,cnt;long long d;map<string,int>q;long long  m[160][160];string s1,t1,x,y;int main(){    while(~scanf("%d",&n)){        if(n==-1) return 0;        cnt=0;        for(i=1;i<=150;i++)         for(j=1;j<=150;j++)          if(i==j) m[i][j]=0;          else  m[i][j]=Inf;        q.clear();                cin>>s1>>t1;                for(i=1;i<=n;i++){            cin>>x>>y>>d;            if(q.find(x)==q.end())  q[x]=++cnt;            if(q.find(y)==q.end())  q[y]=++cnt;            if(m[q[x]][q[y]]>d) m[q[x]][q[y]]=d;            if(m[q[y]][q[x]]>d) m[q[y]][q[x]]=d;        }        for(k=1;k<=cnt;k++)         for(i=1;i<=cnt;i++)          for(j=1;j<=cnt;j++)           if(m[i][k]+m[k][j]<m[i][j]) m[i][j]=m[i][k]+m[k][j];        if(q[s1]>=1&&q[t1]>=1&&m[q[s1]][q[t1]]!=Inf) cout<<m[q[s1]][q[t1]]<<endl;        else cout<<"-1"<<endl;    }    return 0;

HDU2066#include<cstdio>#include<cstdlib>#include<iostream>#include<memory.h>#include<queue>using namespace std;queue<int>q;const int Inf=0x3f3f3f3f;;const int Maxm=3000100;const int Maxn=1010;int dis[Maxn],cnt,n,Min,c,dr;int Laxt[Maxm],Next[Maxm],To[Maxm],Len[Maxm];int conti[Maxn],dream[Maxn];int Win[Maxn];void _add(int u,int v,int d){    Next[++cnt]=Laxt[u];    Laxt[u]=cnt;    To[cnt]=v;    Len[cnt]=d;        Next[++cnt]=Laxt[v];    Laxt[v]=cnt;    To[cnt]=u;    Len[cnt]=d;}void _dij(){    while(!q.empty()){       int s=q.front();       q.pop();       Win[s]=0;       for(int i=Laxt[s];i>0;i=Next[i]){              if(dis[s]+Len[i]<dis[To[i]])              {                dis[To[i]]=dis[s]+Len[i];                if(!Win[To[i]]) {                     q.push(To[i]);                    Win[To[i]]=1;                 }            }        }    }}int main(){    int m,i,j,k,x,y,z;    while(cin>>m>>c>>dr)    {        memset(Laxt,0,sizeof(Laxt));        memset(Next,0,sizeof(Next));        memset(Win,0,sizeof(Win));        cnt=1;         for(i=1;i<=m;i++) {            scanf("%d%d%d",&x,&y,&z);            _add(x,y,z);            dis[x]=Inf;            dis[y]=Inf;        }        for(i=1;i<=c;i++) {          scanf("%d",&conti[i]);          dis[conti[i]]=0;          q.push(conti[i]);          Win[conti[i]]=1;        }        for(i=1;i<=dr;i++) {          scanf("%d",&dream[i]);          dis[dream[i]]=Inf;        }        _dij();        Min=Inf;        for(j=1;j<=dr;j++)         if(Min>dis[dream[j]]) {           Min=dis[dream[j]];         }        printf("%d\n",Min);    }        return 0;}

HDU4284

HDU4284#include<cstdio>#include<cstdlib>#include<iostream>#include<memory.h>#include<algorithm>using namespace std;const int inf=0x3fffffff;int Map[110][110];int City[20],Ci[20],Di[20];int n,m,Mon,H,T;int used[120]; bool ok;void _tempt(int u,int k,int tmp){      if(k==H)       if(tmp>=Map[u][1]){            ok=true;            return ;       }      for(int i=1;i<=H;i++){            if(used[City[i]]!=T&&Map[u][City[i]]!=inf){                 if(tmp-Map[u][City[i]]>=Di[i])                  {                            used[City[i]]=T;                        _tempt(City[i],k+1,tmp-Map[u][City[i]]-Di[i]+Ci[i]);                  }                 if(ok) return ;                 used[City[i]]=0;            }      }}int main(){    int x,y,z,i,j,k;    scanf("%d",&T);    while(T--){        scanf("%d%d%d",&n,&m,&Mon);        for(i=0;i<=n;i++)         for(j=0;j<=n;j++)         if(i==j) Map[i][j]=0;         else Map[i][j]=inf;                  for(i=1;i<=m;i++){           scanf("%d%d%d",&x,&y,&z);           if(z<Map[x][y]) Map[x][y]=z;           if(z<Map[y][x]) Map[y][x]=z;        }                for(k=1;k<=n;k++)         for(i=1;i<=n;i++)          for(j=1;j<=n;j++)           if(Map[i][j]>Map[i][k]+Map[k][j])            Map[i][j]=Map[i][k]+Map[k][j];                    scanf("%d",&H);        for(i=1;i<=H;i++)          scanf("%d%d%d",&City[i],&Ci[i],&Di[i]);        ok=false;        _tempt(1,0,Mon);        if(ok) printf("YES\n");        else printf("NO\n");    }    return 0;} 

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