POJ 3169 Layout 差分约束系统
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//#pragma comment(linker, "/STACK:1024000000,1024000000") #include<cstdio> #include<cstring> #include<cstdlib> #include<algorithm> #include<iostream> #include<sstream> #include<cmath> #include<climits> #include<string> #include<map> #include<queue> #include<vector> #include<stack> #include<set> using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair<int,int> pii; #define pb(a) push(a) #define INF 0x1f1f1f1f #define lson idx<<1,l,mid #define rson idx<<1|1,mid+1,r #define PI 3.1415926535898 template<class T> T min(const T& a,const T& b,const T& c) { return min(min(a,b),min(a,c)); } template<class T> T max(const T& a,const T& b,const T& c) { return max(max(a,b),max(a,c)); } void debug() { #ifdef ONLINE_JUDGE #else freopen("in.txt","r",stdin); //freopen("d:\\out1.txt","w",stdout); #endif } int getch() { int ch; while((ch=getchar())!=EOF) { if(ch!=' '&&ch!='\n')return ch; } return EOF; } struct Edge { int u,v; ll w; bool operator < (const Edge &ant) const { return w<ant.w; } }; const int maxn=1005; int n; vector<int> g[maxn]; vector<Edge> edge; void init() { for(int i=1;i<=n;i++) g[i].clear(); edge.clear(); } void add(int u,int v,ll w) { Edge e=(Edge){u,v,w}; edge.push_back(e); g[u].push_back(edge.size()-1); } ll d[maxn]; bool inq[maxn]; int cnt[maxn]; bool solve() { for(int i=1;i<=n;i++) { d[i]=INF; cnt[i]=inq[i]=0; } d[1]=0; inq[1]=1; queue<int> q; q.push(1); while(!q.empty()) { int u=q.front();q.pop(); inq[u]=false; for(int i=0;i<g[u].size();i++) { Edge &e=edge[g[u][i]]; if(d[u]+e.w<d[e.v]) { d[e.v]=d[u]+e.w; if(!inq[e.v]) { q.push(e.v); inq[e.v]=true; if(++cnt[e.v]>n)return true; } } } } return false; } int main() { int A,B; while(scanf("%d%d%d",&n,&A,&B)!=EOF) { init(); for(int i=0;i<A;i++) { int a,b,w; scanf("%d%d%d",&a,&b,&w); if(a>b)swap(a,b); add(a,b,w); } for(int i=0;i<B;i++) { int a,b,w; scanf("%d%d%d",&a,&b,&w); if(a>b)swap(a,b); add(b,a,-w); } for(int i=1;i<n;i++) add(i+1,i,0); bool x=solve(); if(x) printf("-1\n"); else if(d[n]==INF) printf("-2\n"); else printf("%I64d\n",d[n]); } return 0; }