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  • LUOGU P1342 请柬

    建正、反向图,分别跑spfa/dij,然后统计两次所有点的距离的和。

    一开始想偷懒,建一个图,然后通过边的编号的奇偶性判断它是正/反向图,可是聪明反被聪明误,tle了

    QAQ

    偷懒不成反倒吃亏。

     1 #include<bits/stdc++.h>
     2 #pragma GCC optimize(3)
     3 namespace ZDY{
     4     #define res register
     5     #define ri res int
     6     #define ll long long
     7     #define db double
     8     #define il inline
     9     #define MB template <class T>
    10     #define Fur(i,x,y) for(ri i=x;i<=y;i++)
    11     #define fur(i,x,y) for(i=x;i<=y;i++)
    12     #define Fdr(i,x,y) for(ri i=x;i>=y;i--)
    13     #define in2(x,y) in(x),in(y)
    14     #define in3(x,y,z) in2(x,y),in(z)
    15     #define in4(a,b,c,d) in2(a,b);in2(c,d)
    16     #define outn(x) out(x),pc('
    ')
    17     #define clr(x,y) memset(x,y,sizeof(x))
    18     #define cpy(x,y) memcpy(x,y,sizeof(x))
    19     #define fl(i,x) for(ri i=head[x],to;to=e[i].to,i;i=e[i].nxt)
    20     #define inf 2147483647
    21     #define fin(s) freopen(s".in","r",stdin)
    22     #define fout(s) freopen(s".out","w",stdin)
    23     #define gt io.gc()
    24     MB il T ABS(T x){return x>0?x:-x;}
    25     MB il T MAX(T x,T y){return x>y?x:y;}
    26     MB il T MIN(T x,T y){return x<y?x:y;}
    27     MB il T GCD(T x,T y){return y?GCD(y,x%y):x;}
    28     MB il void SWAP(T x,T y){T t=x;y=t;x=y;}
    29 }using namespace ZDY;using namespace std;
    30 
    31 class IO{
    32    #define fok (ch!=EOF)
    33    #define sep (ch==' '||ch=='
    '||ch=='	')
    34    #define dsep !isdigit(ch)
    35    #define neq(a,b) ((a)-(b)>1e-6)
    36    char rbuf[1000002],wbuf[1000002],b,*p1,*p2;
    37    int rs,ws,S;
    38    public:
    39        IO():p1(rbuf),p2(wbuf),S(1000000),rs(1000000),ws(-1),b(1){}
    40        ~IO(){fwrite(wbuf,1,ws+1,stdout);}
    41        il char gc(){return rs==S&&(p1=rbuf,rs=-1,(S=fread(rbuf,1,S+1,stdin)-1)==-1)?(b=0,EOF):(++rs,*p1++);}
    42        il void pc(int x){ws==1000000&&(p2=wbuf,ws=-1,fwrite(wbuf,1,1000001,stdout)),++ws,*p2++=x;}
    43        il void puts(const char str[]){fwrite(wbuf,1,ws+1,stdout)?(ws=-1):0,fwrite(str,1,strlen(str),stdout);}
    44        il void gl(string& s){for(res char ch;(ch=gc())!='
    '&&fok;)s+=ch;}
    45        il IO& operator>>(int& x){x=0;res char f=0,ch=gc();while(dsep&&fok)f|=(ch=='-'),ch=gc();while(isdigit(ch))x=(x<<1)+(x<<3)+(ch^48),ch=gc();return x=f?-x:x,*this;}
    46        il IO& operator>>(ll& x){x=0;res char f=0,ch=gc();while(dsep&&fok)f|=(ch=='-'),ch=gc();while(isdigit(ch))x=(x<<1)+(x<<3)+(ch^48),ch=gc();return x=f?-x:x,*this;}
    47        il IO& operator>>(char& ch){return ch=gc(),*this;}
    48        il IO& operator>>(string& s){res char ch=gc();while(sep&&fok)ch=gc();while(!sep&&fok)s+=ch,ch=gc();return *this;}
    49        il IO& operator>>(double& x){x=0;res char f=0,ch=gc();double d=0.1;while(dsep&&fok)f|=(ch=='-'),ch=gc();while(isdigit(ch))x=x*10+(ch^48),ch=gc();if(ch=='.')while(isdigit(ch=gc()))x+=d*(ch^48),d*=0.1;return x=f?-x:x,*this;}
    50        il IO& operator<<(int x){res char ch[10],i=-1;!x?(pc('0'),0):0,x<0?(pc('-'),x=-x):0;while(x)ch[++i]=x%10+48,x/=10;while(~i)pc(ch[i]),--i;return *this;}
    51        il IO& operator<<(ll x){res char ch[20],i=-1;!x?(pc('0'),0):0,x<0?(pc('-'),x=-x):0;while(x)ch[++i]=x%10+48,x/=10;while(~i)pc(ch[i]),--i;return *this;}
    52        il IO& operator<<(char ch){return pc(ch),*this;}
    53        il IO& operator<<(char str[]){return puts(str),*this;}
    54        il IO& operator<<(double x){int y=int(x);*this<<y;x-=y;while(neq(x,int(x)))x*=10;x?*this<<'.'<<int(x):0;return *this;}
    55        il operator bool(){return b;}
    56 }io;
    57 
    58 #define N 1000001
    59 #define Fl(i,x) for(ri i=Head[x],to;to=E[i].to,i;i=E[i].nxt)
    60 int n,m,head[N],Head[N],cnt=0,Cnt=0;
    61 ll d[N],ans=0;
    62 bool v[N];
    63 struct cmp{bool operator()(int a,int b){return d[a]>d[b];}};
    64 struct edge{int to,w,nxt;}e[N],E[N];
    65 il void add(int x,int y,int w){e[++cnt].to=y;e[cnt].w=w;e[cnt].nxt=head[x];head[x]=cnt;}
    66 il void ADD(int x,int y,int w){E[++Cnt].to=y;E[Cnt].w=w;E[Cnt].nxt=Head[x];Head[x]=Cnt;}
    67 priority_queue<int,vector<int>,cmp>q;
    68 il void spfa(int p){
    69     Fur(i,2,n)d[i]=1e15;
    70     d[1]=0;q.push(1);
    71     int x;
    72     while(!q.empty()){
    73         v[x=q.top()]=0;q.pop();
    74         if(p){
    75             fl(i,x)
    76             if(d[x]+e[i].w<d[to]){
    77                 d[to]=d[x]+e[i].w;
    78                 if(!v[to])q.push(to),v[to]=1;
    79             }
    80         }
    81         else{
    82             Fl(i,x)
    83             if(d[x]+E[i].w<d[to]){
    84                 d[to]=d[x]+E[i].w;
    85                 if(!v[to])q.push(to),v[to]=1;
    86             }
    87         } 
    88     }
    89 }
    90 int main(){
    91     io>>n>>m;
    92     int x,y,w;
    93     Fur(i,1,m)io>>x>>y>>w,add(x,y,w),ADD(y,x,w);
    94     Fur(i,0,1){spfa(i);Fur(j,1,n)ans+=d[j];}
    95     io<<ans<<'
    ';
    96 }
    献上复活的spfa
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  • 原文地址:https://www.cnblogs.com/mimiorz/p/9736201.html
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