【Bzoj1901】Dynamic Ranking

题意

给一个序列，每次询问[l,r]区间内第k小的数字。带修改。

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解析

同2B平衡树的操作。
操作少可以打得简单一点。

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#include <cstdio>#include <algorithm>#define Rep( i , _begin , _end ) for(int i=(_begin),i##_END=(_end);i<=(i##_END);i++)#define For( i , _begin , _end ) for(int i=(_begin),i##_END=(_end);i!=(i##_END);i++)#define Lop( i , _begin , _end ) for(int i=(_begin),i##_END=(_end);i>=(i##_END);i++)#define Dnt( i , _begin , _end ) for(int i=(_begin),i##_END=(_end);i!=(i##_END);i++)using std :: max;using std :: min;const int maxx = (10000 << 2) + 25;const int maxm = 10000 * 4 * 16 + 25;const int Inf = 1000000000;int n,m,x,y,z,k,num,ans,f;int ch[maxm][2],fix[maxm],v[maxm],size[maxm],cnt[maxm];int rt[maxx],a[maxx];char s[10];namespace Treap{    int chk(int x,int y) {return x == y? 20011025 : x > y;}    void upt(int i) {size[i] = size[ch[i][0]] + size[ch[i][1]] + cnt[i];}    void rotate(int &i,int f){        int t = ch[i][f];        ch[i][f] = ch[t][f^1];        ch[t][f^1] = i;        size[t] = size[i];        upt(i);i = t;    }    void insert(int &i,int x){        if(!i) {v[i=++num] = x;size[i] = cnt[i] = 1;fix[i] = rand();return;}        size[i] ++;        if(v[i] == x) {cnt[i] ++;return;}        int tmp = chk(x,v[i]);        insert(ch[i][tmp],x);        if(fix[ch[i][tmp]] < fix[i]) rotate(i,tmp);    }    void remove(int &i,int x){        if(!i) return;        int tmp = chk(x,v[i]);        if(x != v[i]) size[i] --,remove(ch[i][tmp],x);        if(x == v[i]){            if(cnt[i] > 1) {cnt[i] --;size[i] --;return;}            if(ch[i][0] * ch[i][1] == 0) {i = ch[i][0] + ch[i][1];return;}            tmp = chk(fix[ch[i][0]],fix[ch[i][1]]);            rotate(i,tmp);remove(i,x);        }    }    int Dfs(int i,int x){        if(v[i] == x) return cnt[i];        if(!i) return 0;        return x < v[i]? Dfs(ch[i][0],x) : Dfs(ch[i][1],x);    }    int Qrank(int i,int x){        if(!i) return 0;        if(v[i] == x) return size[ch[i][0]];        else return x <= v[i]? Qrank(ch[i][0],x) : cnt[i] + size[ch[i][0]] + Qrank(ch[i][1],x);    }}namespace Segment_Tree{    using namespace Treap;    void Build(int t,int l,int r){        Rep( i , l , r ) insert(rt[t],a[i]);        if(l == r) return;int mid = (l+r) >> 1;        Build(t<<1,l,mid);Build(t<<1|1,mid+1,r);    }    void modify(int i,int pos,int l,int r,int k){        remove(rt[i],a[pos]);        insert(rt[i],k);        if(l == r) return;int mid = (l+r) >> 1;        if(pos <= mid) modify(i<<1,pos,l,mid,k);        if(pos >  mid) modify(i<<1|1,pos,mid+1,r,k);    }    int Query(int i,int x,int y,int l,int r,int k){        if(x <= l && r <= y) return Qrank(rt[i],k);        int mid = (l+r) >> 1;int ans = 0;        if(x <= mid) ans += Query(i<<1,x,y,l,mid,k);        if(y >  mid) ans += Query(i<<1|1,x,y,mid+1,r,k);        return ans;     }    int Ex_Order(int x,int y,int k){        int l = 0,r = Inf,ans;        while(l <= r){            int mid = (l+r) >> 1;            if(Query(1,x,y,1,n,mid) + 1 <= k) ans = mid,l = mid + 1;            else r = mid - 1;        }        return ans;    }}namespace Bit{    using namespace Treap;    void Add(int x,int k,int f){        for(int i=x;i<=n;i+=i&(-i))            f? insert(rt[i],k) : remove(rt[i],k);    }    int Query_B(int x,int k){        int ans = 0;        for(int i=x;i;i-=i&(-i))            ans += Qrank(rt[i],k);        return ans;    }    int Ex_Order_B(int x,int y,int k){        int l = 0,r = Inf,ans;        while(l <= r){            int mid = (l+r) >> 1;            if(Query_B(y,mid) - Query_B(x-1,mid) + 1 <= k) ans = mid,l = mid + 1;            else r = mid - 1;        }        return ans;    }}using namespace Segment_Tree;using namespace Bit;int main(){    scanf("%d%d",&n,&m);    Rep( i , 1 , n ) scanf("%d",&a[i]);    Rep( i , 1 , n ) Add(i,a[i],1);    while( m-- ){        scanf("%s",s);        if(s[0] == 'C') scanf("%d%d",&x,&y),Add(x,a[x],0),Add(x,y,1),a[x] = y;        if(s[0] == 'Q') scanf("%d%d%d",&x,&y,&z),printf("%d\n",Ex_Order_B(x,y,z));    }    return 0;}