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。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
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 }