NOIP 模拟 $11; m english$

题解

本题有一定代码难度

对于需要区间最大值,可以反过来考虑,先预处理出每个数所能扩展的最大边界,也就是说,求出一个最大的区间,其最大值为这个数,单调栈 (mathcal O(n)) 求解

那么对于第一问,我们记录一个数组 (bit)(bit_{i,j}) 表示前 (i) 个数二进制下第 (j) 位为 (1) 的有多少

对于每一个数,设其左边界为 (l_i),右边界为 (r_i),则我们将这个区间分成两部分 (l_i~i)(i~r_i),选取数少的枚举

枚举每一位,若这个数这一为不为 (1),则贡献为 (r_i-i+1-(bit_{r_i,j}-bit_{i-1,j})),为 (0) 同理。

那么对于第二问,我们可以建一颗 (01trie)

个人认为,可持久化 (01trie) 就相当于 (01trie) 前缀和,可以方便得求区间值

所以,我们这一问求得就是对于一个在 (num_j,jin [l_i,i]) 有多少 (k) 满足 ({num_j};;xor;;{num_k} > num_i)(01trie) 求解即可

Code:
#include<bits/stdc++.h>
#define ri register signed
#define p(i) ++i
using namespace std;
namespace IO{
    char buf[1<<21],*p1=buf,*p2=buf;
    #define gc() p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++
    template<typename T>inline void read(T &x) {
        ri f=1;x=0;register char ch=gc();
        while(ch<'0'||ch>'9') {if (ch=='-') f=0;ch=gc();}
        while(ch>='0'&&ch<='9') {x=(x<<1)+(x<<3)+(ch^48);ch=gc();}
        x=f?x:-x;
    }
}
using IO::read;
namespace nanfeng{
    #define FM(x) x>=MOD?x-MOD:x
    #define cmax(x,y) ((x)>(y)?(x):(y))
    #define cmin(x,y) ((x)>(y)?(y):(x))
    #define FI FILE *IN
    #define FO FILE *OUT
    typedef long long ll;
    static const int N=1e5+7,MOD=1e9+7;
    int que[N],num[N],l[N],r[N],bit[N][21],cm[21],pce,n,opt;
    ll tmp[21],nmc[21],ans1,ans2;
    struct Trie{
        #define ls(x) T[x].ch[0]
        #define rs(x) T[x].ch[1]
        struct trie{int ch[2],nm;}T[N*22];
        int rt[N],tot;
        inline void insert(int x,int pre,int &nw) {
            nw=p(tot);ri cur=nw;
            for (ri i(20);~i;--i) {
                int p=(x>>i)&1;
                T[cur].nm=T[pre].nm+1;
                T[cur].ch[p^1]=T[pre].ch[p^1];
                T[cur].ch[p]=p(tot);
                cur=T[cur].ch[p],pre=T[pre].ch[p];
            }
            T[cur].nm=T[pre].nm+1;
        }
        inline int query(int sl,int pre,int cur) {
            ri res=0,nm=0;
            for (ri i(20);~i;--i) {
                if (sl&cm[i]) {
                    if (nm+cm[i]>pce) {
                        int k=res;
                        res+=T[ls(cur)].nm-T[ls(pre)].nm;
                        cur=rs(cur),pre=rs(pre);
                        
                    } else {
                        nm+=cm[i];
                        cur=ls(cur),pre=ls(pre);
                    }
                } else {
                    if (nm+cm[i]>pce) {
                        int k=res;
                        res+=T[rs(cur)].nm-T[rs(pre)].nm;
                        cur=ls(cur),pre=ls(pre);
                    } else {
                        nm+=cm[i];
                        cur=rs(cur),pre=rs(pre);
                    }
                }
            }
            return res;
        }
    }T;
    inline void add(int x,int p) {
        for (ri i(0);i<=20;p(i)) {
            bit[p][i]=x&1;x>>=1;
            if (!x) return;
        }
    }
    inline int main() {
        // FI=freopen("nanfeng.in","r",stdin);
        // FO=freopen("nanfeng.out","w",stdout);
        read(n),read(opt);
        cm[0]=1;
        for (ri i(1);i<=20;p(i)) cm[i]=cm[i-1]<<1; 
        for (ri i(1);i<=n;p(i)) read(num[i]);
        ri tl=0;
        for (ri i(1);i<=n;p(i)) {
            add(num[i],i);
            T.insert(num[i],T.rt[i-1],T.rt[i]);
            while(tl&&num[que[tl]]<=num[i]) r[que[tl--]]=i-1;
            l[i]=que[tl]+1;
            que[p(tl)]=i;
            for (ri j(0);j<=20;p(j)) bit[i][j]+=bit[i-1][j];
        } 
        while(tl) r[que[tl--]]=n;
        for (ri i(1);i<=n;p(i)) {
            register ll res1=0,res2=0;
            pce=num[i];
            if (i-l[i]<=r[i]-i) {
                for (ri j(0);j<=20;p(j)) nmc[j]=bit[r[i]][j]-bit[i-1][j]; 
                ri len=r[i]-i+1;
                for (ri j(l[i]);j<=i;p(j)) {
                    for (ri k(0);k<=20;p(k)) {
                        if (num[j]&(1<<k)) tmp[k]=len-nmc[k];
                        else tmp[k]=nmc[k];
                        res1+=tmp[k]*cm[k]%MOD;
                        res1=FM(res1);
                    }
                    res2+=T.query(num[j],T.rt[i-1],T.rt[r[i]])%MOD;
                    res2=FM(res2);
                }
            } else {
                for (ri j(0);j<=20;p(j)) nmc[j]=bit[i][j]-bit[l[i]-1][j]; 
                ri len=i-l[i]+1;
                for (ri j(i);j<=r[i];p(j)) {
                    for (ri k(0);k<=20;p(k)) {
                        if (num[j]&(1<<k)) tmp[k]=len-nmc[k];
                        else tmp[k]=nmc[k];
                        res1+=tmp[k]*cm[k]%MOD;
                        res1=FM(res1);
                    }
                    res2+=T.query(num[j],T.rt[l[i]-1],T.rt[i])%MOD;
                    res2=FM(res2); 
                }
            }
            ans1+=res1*num[i]%MOD,ans1=FM(ans1);
            ans2+=res2*num[i]%MOD,ans2=FM(ans2);
        }
        if (opt==1) printf("%lld
",ans1);
        else if (opt==2) printf("%lld
",ans2);
        else if (opt==3) printf("%lld
%lld
",ans1,ans2);
        return 0;
    } 
}
int main() {return nanfeng::main();}
原文地址:https://www.cnblogs.com/nanfeng-blog/p/14999333.html