洛谷4951 地震
1 #include<iostream> 2 #include<cstdio> 3 #include<algorithm> 4 #define go(i,a,b) for(register int i=a;i<=b;i++) 5 #define ll long long 6 #define db long double 7 #define M 10001 8 #define N 401 9 #define inf 1e15 10 #define eps 1e-12 11 using namespace std; 12 ll read() 13 { 14 ll x=0,y=1;char c=getchar(); 15 while(c<'0'||c>'9') {if(c=='-') y=-1;c=getchar();} 16 while(c>='0'&&c<='9') {x=(x<<1)+(x<<3)+c-'0';c=getchar();} 17 return x*y; 18 } 19 struct node{int u,v;ll t,c;db w;}a[M]; 20 ll n,m,f,fa[N]; 21 int find(int x){if(x==fa[x])return x;return fa[x]=find(fa[x]);} 22 bool cmp(node x,node y){return x.w<y.w;} 23 bool ck(db x) 24 { 25 go(i,1,m) a[i].w=a[i].c+a[i].t*x/1e7; 26 db ans=f+eps;//这里加eps是为了保证精度 27 //----------------------------- 28 sort(a+1,a+m+1,cmp); 29 go(i,1,n) fa[i]=i; 30 go(i,1,m) 31 { 32 int uf=find(a[i].u),vf=find(a[i].v); 33 if(uf==vf) continue; 34 fa[uf]=vf; 35 ans-=a[i].w; 36 if(ans<0)return 0; 37 }//---------------------------最小生成树 38 return 1; 39 } 40 int main() 41 { 42 freopen("quake.in","r",stdin); 43 freopen("quake.out","w",stdout); 44 n=read();m=read();f=read(); 45 db l=1,r=inf; 46 go(i,1,m) a[i].u=read(),a[i].v=read(),a[i].c=read(),a[i].t=read(); 47 if(!ck(0)) {printf("0.0000");return 0;} 48 while(l<r) 49 { 50 db mid=(l+r)/2; 51 if(ck(mid+1)) l=mid+1; 52 else r=mid; 53 } 54 printf("%.4Lf",l/(db)1e7); 55 return 0; 56 }
bzoj1816扑克牌
1 #include<iostream> 2 #include<cstdio> 3 #define go(i,a,b) for(register int i=a;i<=b;i++) 4 #define ll long long 5 #define M 1000001 6 #define inf 1e12 7 using namespace std; 8 ll read() 9 { 10 ll x=0,y=1;char c=getchar(); 11 while(c<'0'||c>'9') {if(c=='-') y=-1;c=getchar();} 12 while(c>='0'&&c<='9') {x=(x<<1)+(x<<3)+c-'0';c=getchar();} 13 return x*y; 14 } 15 int n,m; 16 ll ct,c[M],l,r=inf; 17 bool ck(ll x) 18 { 19 ll nm=min(x,(ll)m); 20 go(i,1,n){if(c[i]<x)nm=nm-(x-c[i]);if(nm<0)return 0;} 21 return 1; 22 } 23 int main() 24 { 25 freopen("cards.in","r",stdin); 26 freopen("cards.out","w",stdout); 27 n=read();m=read(); 28 go(i,1,n) c[i]=read(); 29 while(l<r) 30 { 31 ll mid=(l+r)>>1; 32 if(ck(mid+1)) l=mid+1; 33 else r=mid; 34 } 35 printf("%lld",l); 36 return 0; 37 }
洛谷3199最小圈
1 #include<iostream> 2 #include<cstdio> 3 #define R register 4 #define go(i,a,b) for(R int i=a;i<=b;i++) 5 #define db long double 6 #define M 10001 7 #define N 3001 8 #define inf 1e10 9 #define eps 1e-10 10 using namespace std; 11 int rd() 12 { 13 int x=0,y=1;char c=getchar(); 14 while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();} 15 while(c>='0'&&c<='9'){x=(x<<1)+(x<<3)+c-'0';c=getchar();} 16 return x*y; 17 } 18 int n,m,b[N],cnt; 19 bool in[N],flag; 20 db dis[N]; 21 struct node{int v,nt;db w;}a[M]; 22 void add(int u,int v,db w){a[++cnt].nt=b[u];a[cnt].v=v;a[cnt].w=w;b[u]=cnt;} 23 void ck(int u,db x) 24 { 25 in[u]=1; 26 for(R int i=b[u];i;i=a[i].nt) 27 { 28 int v=a[i].v;db w=a[i].w; 29 if(dis[u]+w-x<dis[v]) 30 { 31 if(in[v]||flag){flag=1;return;} 32 dis[v]=dis[u]+w-x; 33 ck(v,x); 34 } 35 } 36 in[u]=0; 37 } 38 int main() 39 { 40 n=rd();m=rd(); 41 go(i,1,m){int u=rd(),v=rd();db w;scanf("%Lf",&w);add(u,v,w);} 42 db l=-inf,r=inf; 43 while(r-l>eps) 44 { 45 db mid=(l+r)/2;flag=0; 46 go(i,1,n){in[i]=0;dis[i]=0;} 47 go(i,1,n){ck(i,mid);if(flag)break;} 48 if(flag) r=mid; 49 else l=mid; 50 } 51 printf("%.8Lf",l); 52 return 0; 53 }