NOIP 模擬 $24\; \rm graph$
阿新 • • 發佈:2021-07-31
題解
#include<bits/stdc++.h> #define ri register signed #define p(i) ++i using namespace std; namespace IO{ char buf[1<<21],*p1=buf,*p2=buf,OPUT[100]; #define gc() p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?(-1):*p1++; template<typename T>inline void read(T &x) { ri f=1;x=0;register char ch=gc(); while(!isdigit(ch)) {if (ch=='-') f=0;ch=gc();} while(isdigit(ch)) {x=(x<<1)+(x<<3)+(ch^48);ch=gc();} x=f?x:-x; } template<typename T>inline void print(T x,char t) { if (x<0) putchar('-'),x=-x; if (!x) return putchar('0'),(void)putchar(t); ri cnt(0); while(x) OPUT[p(cnt)]=x%10,x/=10; for (ri i(cnt);i;--i) putchar(OPUT[i]^48); return (void)putchar(t); } } using IO::read;using IO::print; namespace nanfeng{ #define FI FILE *IN #define FO FILE *OUT template<typename T>inline T cmax(T x,T y) {return x>y?x:y;} template<typename T>inline T cmin(T x,T y) {return x>y?y:x;} typedef long long ll; static const int N=1e3+7,INF=1061109567; map<int,int> mp; int first[N],wai[N<<1],que[N*100],vis[N],ans[N],W,tot,t=1,n,m; struct edge{int v,w,nxt;}e[N<<2]; ll disf[N],disr[N]; inline void add(int u,int v,int w) { e[t].v=v,e[t].w=w,e[t].nxt=first[u],first[u]=t++; e[t].v=u,e[t].w=w,e[t].nxt=first[v],first[v]=t++; } inline void spfaf() { memset(disf,127,sizeof(ll)*(n+1)); ri hd=1,tl=0; int x=1; disf[que[p(tl)]=x]=0; while(hd<=tl) { vis[x=que[hd++]]=0; for (ri i(first[x]),v;i;i=e[i].nxt) { int w=(e[i].w==-1)?W:e[i].w; if (disf[v=e[i].v]>disf[x]+w) { disf[v]=disf[x]+w; if (!vis[v]) vis[que[p(tl)]=v]=1; } } } } inline void spfar() { memset(disr,127,sizeof(ll)*(n+1)); ri hd=1,tl=0; int x=n; disr[que[p(tl)]=x]=0; while(hd<=tl) { vis[x=que[hd++]]=0; for (ri i(first[x]),v;i;i=e[i].nxt) { int w=(e[i].w==-1)?W:e[i].w; if (disr[v=e[i].v]>disr[x]+w) { disr[v]=disr[x]+w; if (!vis[v]) vis[que[p(tl)]=v]=1; } } } } inline void solve(int w) { W=w; spfaf(),spfar(); for (ri i(1);i<=n;p(i)) if (disf[i]+disr[i]==disf[n]) ans[i]=1; } inline int main() { //FI=freopen("nanfeng.in","r",stdin); //FO=freopen("nanfeng.out","w",stdout); read(n),read(m); for (ri i(1),u,v,w;i<=m;p(i)) { read(u),read(v),read(w); if (w!=-1&&mp.find(w)==mp.end()) mp[wai[p(tot)]=w]=1; add(u,v,w); } if (mp.find(0)==mp.end()) wai[p(tot)]=0; wai[p(tot)]=INF; for (ri i(1);i<=tot;p(i)) solve(wai[i]); for (ri i(1);i<=n;p(i)) putchar(ans[i]^48); puts(""); return 0; } } int main() {return nanfeng::main();}