• NOIP 模拟 $84; m 宝藏$


    题解 (by;zjvarphi)

    显然,(x) 越大,答案单调不增,所以可以对 (w) 进行排序,从大往小扫。

    (x) 从小到大,维护一个单调指针。

    假设当前答案为 (p) 位置,那么在 (p) 位置之前一定选 (frac{x}{2}) 个最小的,在其后同理。直接在权值线段树上二分 (frac{x}{2}) 个最小的即可。

    Code
    #include<bits/stdc++.h>
    #define ri signed
    #define pd(i) ++i
    #define bq(i) --i
    #define func(x) std::function<x>
    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)?(-1):*p1++
        #define debug1(x) std::cerr << #x"=" << x << ' '
        #define debug2(x) std::cerr << #x"=" << x << std::endl
        #define Debug(x) assert(x)
        struct nanfeng_stream{
            template<typename T>inline nanfeng_stream &operator>>(T &x) {
                bool f=false;x=0;char ch=gc();
                while(!isdigit(ch)) f|=ch=='-',ch=gc();
                while(isdigit(ch)) x=(x<<1)+(x<<3)+(ch^48),ch=gc();
                return x=f?-x:x,*this;
            }
        }cin;
    }
    using IO::cin;
    namespace nanfeng{
        #define FI FILE *IN
        #define FO FILE *OUT
        template<typename T>inline T cmax(T x,T y) {return x>y?x:y;}
        template<typename T>inline T cmin(T x,T y) {return x>y?y:x;}
        using ll=long long;
        static const int N=3e5+7,MX=1e6+1;
        int ans[N],n,Q,lft;
        ll T,tmp;
        struct Pair{int w,t;}pr[N];
        struct Seg{
            #define ls(x) T[x].l
            #define rs(x) T[x].r
            #define up(x) T[x].sum=T[ls(x)].sum+T[rs(x)].sum,
            T[x].nm=T[ls(x)].nm+T[rs(x)].nm;
            struct segmenttree{ll sum;int l,r,nm;}T[N<<5];
            int tot,rt;
            func(void(int&,int,int,int,int)) update=[&](int &x,int pos,int k,int l,int r) {
                if (!x) x=++tot;
                if (l==r) return T[x].sum+=pos*k,T[x].nm+=k,void();
                int mid=(l+r)>>1;
                if (pos<=mid) update(ls(x),pos,k,l,mid);
                else update(rs(x),pos,k,mid+1,r);
                up(x);
            };
            func(void(int,int,int)) query=[&](int x,int l,int r) {
                if (!x) return;
                if (l==r) return tmp+=1ll*l*lft,void();
                int mid=(l+r)>>1;
                if (T[ls(x)].nm>lft) query(ls(x),l,mid);
                else if (T[ls(x)].nm==lft) tmp+=T[ls(x)].sum,lft=0;
                else lft-=T[ls(x)].nm,tmp+=T[ls(x)].sum,query(rs(x),mid+1,r);
            };
        }T1,T2;
        inline int main() {
            FI=freopen("treasure.in","r",stdin);
            FO=freopen("treasure.out","w",stdout);
            cin >> n >> T >> Q;
            memset(ans+1,-1,sizeof(int)*n);
            for (ri i(1);i<=n;pd(i)) cin >> pr[i].w >> pr[i].t,++pr[i].t;
            std::sort(pr+1,pr+n+1,[](Pair p1,Pair p2) {return p1.w<p2.w;});
            int p=1;
            for (ri i(1);i<n;pd(i)) T1.update(T1.rt,pr[i].t,1,1,MX);
            for (ri i(n);i;bq(i)) {
                int lim=cmin(i-1,n-i);
                while((p>>1)<=lim)
                    if (p==1) {
                        if (pr[i].t<=T+1) ans[p]=pr[i].w,p+=2;
                        else break;
                    } else {
                        lft=p>>1,tmp=0;
                        T1.query(1,1,MX);
                        lft=p>>1;
                        T2.query(1,1,MX);
                        if (tmp+pr[i].t<=T+p) ans[p]=pr[i].w,p+=2;
                        else break;
                    }
                if (p>n) break;
                T1.update(T1.rt,pr[i-1].t,-1,1,MX);
                T2.update(T2.rt,pr[i].t,1,1,MX);
            }
            for (ri i(1),x;i<=Q;pd(i)) cin >> x,printf("%d
    ",x>n?-1:ans[x]);
            return 0;
        }
    }
    int main() {return nanfeng::main();}
    
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  • 原文地址:https://www.cnblogs.com/nanfeng-blog/p/15473809.html
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