四连测Day2

题目：链接: https://pan.baidu.com/s/1ef_9hGBhczW0B4dz5IUKmw 密码: qgjy

T1:

hash后直接二分查询即可

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
inline long long read()
{
    long long f=1,ans=0;char c;
    while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
    while(c>='0'&&c<='9'){ans=ans*10+c-'0';c=getchar();}
    return ans*f;
}
char str[100001];
long long sum[100001];
long long b[100001];
long long bb=27; 
long long maxn=0;
long long l,r,mid;
long long u,v;
bool check(long long x)
{
    long long x1=sum[u+x-1]-sum[u-1]*b[x];
//    cout<<sum[u+x-1]<<" "<<sum[u-1]<<" "<<b[x]<<" "<<x1<<endl;
    long long x2=sum[v+x-1]-sum[v-1]*b[x];
//    cout<<sum[v+x-1]<<" "<<sum[v-1]<<" "<<b[x]<<"  "<<x2<<endl;
    return x1==x2;
}
int main()
{
    b[0]=1;
    for(int i=1;i<=100000;i++) b[i]=b[i-1]*bb; 
    scanf("%s",str+1);
    long long len=strlen(str+1);
    for(long long i=1;i<=len;i++) sum[i]=sum[i-1]*bb+(str[i]-'a'+1);
    long long n=read();
    for(long long i=1;i<=n;i++)
    {
        u=read(),v=read();
        l=1,r=len-max(u,v)+1;
        maxn=0;
        while(l<=r)
        {
            mid=(l+r)/2;
            if(check(mid)) 
            {
                maxn=max(maxn,mid);
                l=mid+1;
            }else r=mid-1;
        }
        printf("%d
",maxn);
    }
}
/*
aabaabab
1
2 7
*/

T2:

因为作者能力有限，数学技巧过于高深，所以先给std，学完以后再重新补写

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
inline int read()
{
    int x=0,t=1,c;
    while(!isdigit(c=getchar()))if(c=='-')t=-1;
    while(isdigit(c))x=x*10+c-'0',c=getchar();
    return x*t;
}
int sig(long long x)
{
    if(x<0)return -1;
    else if(!x)return 0;
    return 1;
}
long long gcd(long long a,long long b){return b?gcd(b,a%b):a;}
class Vector
{
public:
    long long x,y;
    Vector(long long _x=0,long long _y=0)
    {
        x=_x;
        y=_y;
    }
    Vector operator + (const Vector &b) const
    {
        return Vector(x+b.x,y+b.y);
    }
    Vector operator - (const Vector &b) const
    {
        return Vector(x-b.x,y-b.y);
    }
    long long operator * (const Vector &b) const
    {
        return x*b.x+y*b.y;
    }
};
class Line
{
public:
    long long a,b,c;
    Line(Vector v0,Vector v1)
    {
        a=v0.x-v1.x;
        b=v0.y-v1.y;
        swap(a,b);
        a=-a;
        c=gcd(a,b);
        a/=c;
        b/=c;
        c=a*v0.x+b*v0.y;
    }
    Line(long long _a=0,long long _b=1,long long _c=0)
    {
        a=_a;
        b=_b;
        c=_c;
    }
    int side(Vector v)
    {
        return sig(v*Vector(a,b)-c);
    }
}l1,l2;
void Solve()
{
    int n=read();
    Vector v0,v1,u0,u1;
    v0.x=read();v0.y=read();v1.x=read();v1.y=read();
    l1=Line(v0,v1);
    bool res=0;
    while(n--)
    {
        u0.x=read();u0.y=read();u1.x=read();u1.y=read();
        l2=Line(u0,u1);
        if(l1.a*l2.b==l1.b*l2.a)
        {
            if(l1.c*l2.b==l2.c*l1.b)
            {
                long long l0=0,r0=(v1-v0)*(v1-v0),l1=(u0-v0)*(v1-v0),r1=(u1-v0)*(v1-v0);
                if(l0<=r1&&l1<=r0)res=1;
            }
        }
        else
        {
            if(l1.side(u0)!=l1.side(u1)&&l2.side(v0)!=l2.side(v1))res=1;
        }
    }
    if(res)puts("YES");
    else puts("NO");
}
int main()
{
    freopen("intersect.in","r",stdin);
    freopen("intersect.out","w",stdout);
    int T=read();
    while(T--)Solve();
}

T3:

dijkstra倒推，加优先队列优化，设dis[n]=0,dis[i]=min{dis[i],max（最大限制，dis[x(i为起点的终点)]+所对应需要的能量）}

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<queue>
using namespace std;
inline long long read()
{
    long long f=1,ans=0;char c;
    while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
    while(c>='0'&&c<='9'){ans=ans*10+c-'0';c=getchar();}
    return ans*f;
}
priority_queue<pair<long long,long long > >  que;
long long n,m,cnt=1;
struct node{
    long long a,b,c,m,nex;
}x[2000110];
long long head[1000010];
long long vis[1000010];
long long dis[1000010];
void add(long long u,long long v,long long c,long long m)
{
    x[cnt].a=u,x[cnt].b=v,x[cnt].c=c,x[cnt].m=m;
    x[cnt].nex=head[u],head[u]=cnt++;
}
long long inf;
int main()
{
    memset(head,-1,sizeof(head));
    memset(dis,127/3,sizeof(dis));
    inf=dis[1];
    n=read(),m=read();
    for(long long i=1;i<=m;i++)
    {
        long long u=read(),v=read(),c=read(),m=read();
        add(u,v,c,m);
        add(v,u,c,m);
    }
    dis[n]=0;
    que.push(make_pair(0,n));
    while(!que.empty())
    {
        long long xx=que.top().second;que.pop();
        if(vis[xx]==1) continue;
        vis[xx]=1;
        for(long long i=head[xx];i!=-1;i=x[i].nex)
        {
            if(dis[x[i].b]>max(x[i].m,dis[xx]+x[i].c))
            {
                dis[x[i].b]=max(x[i].m,dis[xx]+x[i].c);
                que.push(make_pair(-dis[x[i].b],x[i].b));
            }
            
        }
    }
    if(dis[1]!=inf) cout<<dis[1];
    else cout<<-1;
}