• 【比赛】HNOI2018 寻宝游戏



    考试的时候就拿了30points滚粗了
    听说myy对这题的倒推做法很无奈,官方题解在此
    正解思路真的很巧妙,也说的很清楚了
    就是分别考虑每一位,会发现题解中的那个性质,然后把询问的二进制数按照排序后的位置放好,如果有1在0后面,那就肯定puts("0"),否则根据那个式子,每一位都要满足那个条件,最后范围不断缩小,就变成了两个数的差

    #include<bits/stdc++.h>
    #define ui unsigned int
    #define ll long long
    #define db double
    #define ld long double
    #define ull unsigned long long
    const int MAXN=1000+10,MAXM=5000+10,Mod=1e9+7;
    ll total;
    int n,m,q,r[MAXM];
    char bin[MAXM];
    template<typename T> inline void read(T &x)
    {
    	T data=0,w=1;
    	char ch=0;
    	while(ch!='-'&&(ch<'0'||ch>'9'))ch=getchar();
    	if(ch=='-')w=-1,ch=getchar();
    	while(ch>='0'&&ch<='9')data=((T)data<<3)+((T)data<<1)+(ch^'0'),ch=getchar();
    	x=data*w;
    }
    template<typename T> inline void write(T x,char ch='')
    {
    	if(x<0)putchar('-'),x=-x;
    	if(x>9)write(x/10);
    	putchar(x%10+'0');
    	if(ch!='')putchar(ch);
    }
    template<typename T> inline void chkmin(T &x,T y){x=(y<x?y:x);}
    template<typename T> inline void chkmax(T &x,T y){x=(y>x?y:x);}
    template<typename T> inline T min(T x,T y){return x<y?x:y;}
    template<typename T> inline T max(T x,T y){return x>y?x:y;}
    inline ll qexp(ll a,ll b)
    {
    	ll res=1;
    	while(b)
    	{
    		if(b&1)res=res*a%Mod;
    		a=a*a%Mod;
    		b>>=1;
    	}
    	return res;
    }
    struct data{
    	int b[MAXN],id;
    	ll ans;
    	data(){ans=-1;}
    	inline bool operator < (const data &A) const {
    		for(register int i=1;i<=n;++i)
    			if(b[i]!=A.b[i])return b[i]>A.b[i];
    		return false;
    	};
    	inline ll value()
    	{
    		if(~ans)return ans;
    		ans=0;
    		for(register int i=1;i<=n;++i)(ans+=b[i]*qexp(2,n-i))%=Mod;
    		return ans;
    	}
    };
    data infin[MAXM];
    int main()
    {
    	freopen("hunt.in","r",stdin);
    	freopen("hunt.out","w",stdout);
    	read(n);read(m);read(q);
    	for(register int i=1;i<=n;++i)
    	{
    		scanf("%s",bin+1);
    		for(register int j=1;j<=m;++j)infin[j].b[n-i+1]=bin[j]-'0';
    	}
    	for(register int i=1;i<=m;++i)infin[i].id=i;
    	total=qexp(2,n);
    	std::sort(infin+1,infin+m+1);
    	while(q--)
    	{
    		scanf("%s",bin+1);
    		for(register int i=1;i<=m;++i)r[i]=bin[infin[i].id]-'0';
    		int p0=m+1,p1=0;
    		for(register int i=m;i>=1;--i)
    			if(!r[i])p0=i;
    		for(register int i=1;i<=m;++i)
    			if(r[i])p1=i;
    		if(p0<p1)puts("0");
    		else if(p0==1)write((total-infin[1].value()+Mod)%Mod,'
    ');
    		else if(p0==m+1)write(infin[m].value(),'
    ');
    		else write((infin[p0-1].value()-infin[p0].value()+Mod)%Mod,'
    ');
    	}
    	return 0;
    }
    
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  • 原文地址:https://www.cnblogs.com/hongyj/p/8907461.html
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