loj#2721. 「NOI2018」屠龙勇士

题目链接

loj#2721. 「NOI2018」屠龙勇士

题解

首先可以列出线性方程组
方程组转化为在模p意义下的同余方程
因为不保证pp 互素,考虑扩展中国剩余定理合并
方程组是带系数的,我们要做的是在%p意义下把系数除过去,(系数为atk[i])
(atk[i],p[i]) 不等于1时无逆元,此时仍可能有解
很显然无解的情况就是
瞎jb猜的,无解的话就是%p[i]意义下atk[i] != 0 ,a[i] = 0
考虑原方程式ai = atk{i] * x + p[i] * y
方程两边同除gcd(pi,atki)解不变 此时atki,pi此时保证了atki与pi互素
若ai不能被整除也是无解的
扩展crt
着实被winXP下输出lld坑了一把....顺带被自己抄的splay坑了一把

/*
苟活者在淡红的血色中,会依稀看到微茫的希望 
*/

#include<bits/stdc++.h> 
using namespace std; 
inline long long read() { 
long long x; 
scanf("%lld",&x); 
return x; 
} 
int n,m; 
#define LL long long 
const int maxn = 500007; 
LL a[maxn],p[maxn]; // x atk[i] = a[i] ( % p[i]) 
LL atk[maxn],tatk[maxn]; 

struct Splay { 
    #define fa(x) T[x].fa
    #define ls(x) T[x].ch[0]
    #define rs(x) T[x].ch[1]
    #define root T[0].ch[1] 
    struct node
    { 
        LL val,rev,siz,fa,ch[2]; 
    }T[maxn]; 
    LL tot;
    void clear() {
        tot = 0; root = 0;
        for(LL i = 1; i <= maxn; i++) T[i].val = T[i].rev = T[i].siz = T[i].fa = T[i].ch[0] = T[i].ch[1] = 0;
    }
    LL ident(LL x){return T[fa(x)].ch[0]==x?0:1;}
    void connect(LL x,LL fa,LL how){T[fa].ch[how]=x;T[x].fa=fa;}
    void update(LL x){T[x].siz=T[ls(x)].siz+T[rs(x)].siz+T[x].rev;}
    void rotate(LL x) 
    { 
        LL Y=T[x].fa,R=T[Y].fa;
        LL Yson=ident(x),Rson=ident(Y);
        LL B=T[x].ch[Yson^1];
        connect(B,Y,Yson);
        connect(Y,x,Yson^1);
        connect(x,R,Rson);
        update(Y);update(x);
    }
    void splay(LL x,LL to)
    {
        to=T[to].fa;
        while(T[x].fa!=to)
        {
            if(T[fa(x)].fa==to) rotate(x);
            else if(ident(x)==ident(fa(x))) rotate(fa(x)),rotate(x);
            else rotate(x),rotate(x);
        } 
    } 
    LL newnode(LL fa,LL val) { 
        T[++tot].fa=fa;
        T[tot].val=val;
        T[tot].rev=T[tot].siz=1;
        return tot;
    }
    LL find(LL val)
    {
        LL now=root;
        while(1)
        {
            if(T[now].val==val) {splay(now,root);return now;}
            LL nxt=T[now].val<val;
            now=T[now].ch[nxt];
        }
    }
    void insert(LL val)
    {
        if(root==0) {root=newnode(0,val);return ;}
        LL now=root;
        while(1)
        {
            T[now].siz++;
            if(T[now].val==val) {T[now].rev++;splay(now,root);return ;} 
            LL nxt=val<T[now].val?0:1;
            if(!T[now].ch[nxt]) {T[now].ch[nxt]=newnode(now,val);splay(now,root);return ;}
            now=T[now].ch[nxt];
        }
    }
    void erase(LL val)
    {
        LL now=find(val);
        if(T[now].rev>1) {T[now].rev--;T[now].siz--;return ;}
        else if(!ls(now)&&!rs(now)) {root=0;return ;}
        else if(!ls(now)) {root=rs(now);T[rs(now)].fa=0;return ;}
        LL left=ls(now);
        while(rs(left)) left=rs(left);
        splay(left,ls(now));
        connect(rs(now),left,1);
        connect(left,0,1);
        //update(rs(now));
        update(left);//
    }
    LL pre(LL val)
    { 
        LL now=root,ans=-1e13; 
        while(now) 
        { 
            if(T[now].val<=val) ans=max(ans,T[now].val); 
            LL nxt=val<=T[now].val?0:1; 
            now=T[now].ch[nxt]; 
        } 
        return ans == -1e13 ? -1 : ans; 
    } 
    LL nxt(LL val)
    {
        LL now=root,ans=1e13;   
        while(now)
        {
            if(T[now].val>val) ans=min(ans,T[now].val);
            LL nxt=val<T[now].val?0:1;
            now=T[now].ch[nxt];
        }
        return ans;
    }
}Sp;  
LL gcd(LL a,LL b) {return b == 0 ? a : gcd(b,a % b);} 
LL exgcd(LL a,LL b,LL &x,LL &y) { 
    if(b == 0) {x = 1,y = 0;return a; } 
    LL ret = exgcd(b,a % b,x,y);  
    LL tmp = x;x = y;y = tmp - (a / b) * y; 
    return ret; 
} 
LL inv(LL a,LL b) { 
    LL x,y; 
    exgcd(a,b,x,y); 
    while(x < 0) x += b; 
    return x; 
} 
void work() { 
    LL ans = 0; 
    for(int i = 1;i <= n;++ i) { 
        ans = std::max(ans,a[i] % atk[i] == 0 ? a[i] / atk[i] : a[i] / atk[i] + 1); 
    } 
    printf("%lld\n",ans); 
} 
LL M[maxn],C[maxn]; 
inline LL add(LL x,LL y,LL mod) { return x + y >= mod ? x + y - mod : x + y; } 
LL mul(LL x,LL k,LL mod) { 
    LL ret = 0 ;
    x %= mod; 
    for(;k;k >>= 1,x = add(x,x,mod)) 
        if(k & 1) ret = add(ret,x,mod); 
    return ret; 
} 
bool flag = false; 
void init() { 
    Sp.clear(); 
    n = read(),m = read(); 
    flag = false; 
    //puts("haha"); 
    for(int i = 1;i <= n;++ i) a[i] = read(); 
    for(int i = 1;i <= n;++ i){ p[i] = read();if(p[i] != 1) flag = true; } 
    for(int j = 1;j <= n;++ j) tatk[j] = read(); 
    //printf("%d %d %d\n",n,m,flag); 
    for(int k,i = 1;i <= m;++ i) 
        k = read(),Sp.insert(k);  
    for(int i = 1;i <= n;++ i) { 
        //puts("asdasd"); 
        LL p = Sp.pre(a[i]); 
        if(p == -1) p = Sp.nxt(a[i]); 
        atk[i] = p; 
        Sp.erase(p); 
         Sp.insert(tatk[i]); 
    } 
    if(!flag) {work();/*puts("haha");*/return; } 
    int num = 0; 
    for(int i = 1;i <= n;++ i) { 
        a[i] %= p[i],atk[i] %= p[i]; 
        if(!a[i] && !atk[i]) continue; 
        else if(!atk[i]){puts("-1");return;} 
        LL d = gcd(atk[i],p[i]); 
        if(a[i] % d != 0) {continue; } 
        a[i] /= d,atk[i] /= d,p[i] /= d;    
        C[++ num] = mul(a[i] , ((inv(atk[i],p[i]) % p[i] + p[i]) % p[i]),p[i]); 
        M[num] = p[i]; 
    } 
    LL m = M[1],A = C[1],x,y,t; 
    for(int i = 2;i <= num;++ i) { 
        LL d = exgcd(m,M[i],x,y); 
        t = (M[i] / d); 
        //if((C[i]-A)%d == 0 || (a[i] - A) % d == -0 ) {  
            x = mul((x % t + t) % t,(((C[i] - A) / d) % t + t) % t,t); 
            LL MOD = (m / d) * (M[i]); 
            A = (mul(m , x, MOD) + A % MOD) % MOD;
            m = MOD;  
        // else {puts("-1"); return;}; 
    } 
    A = (A % m + m) % m;
    printf("%lld\n",A); 
} 

int main() { 
    freopen("dragon.in","r",stdin); freopen("dragon.out","w",stdout);  
    int t = read(); 
    while(t --) { 
        init(); 
    } 
    return 0; 
} 

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转载自www.cnblogs.com/sssy/p/9345538.html