洛谷4951 地震 bzoj1816扑克牌 洛谷3199最小圈 / 01分数规划

　　

洛谷4951 地震

 #include<iostream>
 #include<cstdio>
 #include<algorithm>
 #define go(i,a,b) for(register int i=a;i<=b;i++)
 #define ll long long
 #define db long double
 #define M 10001
 #define N 401
 #define inf 1e15
 #define eps 1e-12
 using namespace std;
 ll read()
 {
     ll x=,y=;char c=getchar();
     while(c<''||c>'') {if(c=='-') y=-;c=getchar();}
     while(c>=''&&c<='') {x=(x<<)+(x<<)+c-'';c=getchar();}
     return x*y;
 }
 struct node{int u,v;ll t,c;db w;}a[M];
 ll n,m,f,fa[N];
 int find(int x){if(x==fa[x])return x;return fa[x]=find(fa[x]);}
 bool cmp(node x,node y){return x.w<y.w;}
 bool ck(db x)
 {
     go(i,,m) a[i].w=a[i].c+a[i].t*x/1e7;
     db ans=f+eps;//这里加eps是为了保证精度
     //-----------------------------
     sort(a+,a+m+,cmp);
     go(i,,n) fa[i]=i;
     go(i,,m)
     {
         int uf=find(a[i].u),vf=find(a[i].v);
         if(uf==vf) continue;
         fa[uf]=vf;
         ans-=a[i].w;
         if(ans<)return ;
     }//---------------------------最小生成树
     return ;
 }
 int main()
 {
     freopen("quake.in","r",stdin);
     freopen("quake.out","w",stdout);
     n=read();m=read();f=read();
     db l=,r=inf;
     go(i,,m) a[i].u=read(),a[i].v=read(),a[i].c=read(),a[i].t=read();
     if(!ck()) {printf("0.0000");return ;}
     while(l<r)
     {
         db mid=(l+r)/;
         if(ck(mid+)) l=mid+;
         else r=mid;
     }
     printf("%.4Lf",l/(db)1e7);
     return ;
 }

bzoj1816扑克牌

 #include<iostream>
 #include<cstdio>
 #define go(i,a,b) for(register int i=a;i<=b;i++)
 #define ll long long
 #define M 1000001
 #define inf 1e12
 using namespace std;
 ll read()
 {
     ll x=,y=;char c=getchar();
     while(c<''||c>'') {if(c=='-') y=-;c=getchar();}
     while(c>=''&&c<='') {x=(x<<)+(x<<)+c-'';c=getchar();}
     return x*y;
 }
 int n,m;
 ll ct,c[M],l,r=inf;
 bool ck(ll x)
 {
     ll nm=min(x,(ll)m);
     go(i,,n){if(c[i]<x)nm=nm-(x-c[i]);if(nm<)return ;}
     return ;
 }
 int main()
 {
     freopen("cards.in","r",stdin);
     freopen("cards.out","w",stdout);
     n=read();m=read();
     go(i,,n) c[i]=read();
     while(l<r)
     {
         ll mid=(l+r)>>;
         if(ck(mid+)) l=mid+;
         else r=mid;
     }
     printf("%lld",l);
     return ;
 }

洛谷3199最小圈

 #include<iostream>
 #include<cstdio>
 #define R register
 #define go(i,a,b) for(R int i=a;i<=b;i++)
 #define db long double
 #define M 10001
 #define N 3001
 #define inf 1e10
 #define eps 1e-10
 using namespace std;
 int rd()
 {
     int x=,y=;char c=getchar();
     while(c<''||c>''){if(c=='-')y=-;c=getchar();}
     while(c>=''&&c<=''){x=(x<<)+(x<<)+c-'';c=getchar();}
     return x*y;
 }
 int n,m,b[N],cnt;
 bool in[N],flag;
 db dis[N];
 struct node{int v,nt;db w;}a[M];
 void add(int u,int v,db w){a[++cnt].nt=b[u];a[cnt].v=v;a[cnt].w=w;b[u]=cnt;}
 void ck(int u,db x)
 {
     in[u]=;
     for(R int i=b[u];i;i=a[i].nt)
     {
         int v=a[i].v;db w=a[i].w;
         if(dis[u]+w-x<dis[v])
         {
             if(in[v]||flag){flag=;return;}
             dis[v]=dis[u]+w-x;
             ck(v,x);
         }
     }
     in[u]=;
 }
 int main()
 {
     n=rd();m=rd();
     go(i,,m){int u=rd(),v=rd();db w;scanf("%Lf",&w);add(u,v,w);}
     db l=-inf,r=inf;
     while(r-l>eps)
     {
         db mid=(l+r)/;flag=;
         go(i,,n){in[i]=;dis[i]=;}
         go(i,,n){ck(i,mid);if(flag)break;}
         if(flag) r=mid;
         else l=mid;
     }
     printf("%.8Lf",l);
     return ;
 }