主席树
#include <iostream> #include <algorithm> #include <cstdio> #include <cstring> #include <cmath> #include <string> #include <cstdlib> #define maxn 100005 using namespace std; int b[maxn],t[maxn],n,m,size,v[maxn],tot=0; struct chairtree { int l,r,size; }a[maxn*30]; int Build(int l,int r) { int root=++tot; a[root].size=0; if (l==r) return root; int m=(l+r)>>1; a[root].l=Build(l,m); a[root].r=Build(m+1,r); return root; } int Update(int root,int x) { int now=++tot; int tmp=now; a[tot].size=a[root].size+1; int l=1,r=size; while (l<r) { int m=(l+r)>>1; if (x<=m) { a[now].l=++tot; a[now].r=a[root].r; //充分利用原来相同的结点 root=a[root].l; now=tot; r=m; } else { a[now].l=a[root].l; a[now].r=++tot; root=a[root].r; now=tot; l=m+1; } a[now].size=a[root].size+1; } return tmp; } int Ask(int lx,int rx,int k) { int l=1,r=size; while (l<r) { int m=(l+r)>>1; if (a[a[rx].l].size-a[a[lx].l].size>=k) { r=m; lx=a[lx].l; rx=a[rx].l; } else { l=m+1; k-=a[a[rx].l].size-a[a[lx].l].size; lx=a[lx].r; rx=a[rx].r; } } return l; } void Hash1() { sort(b+1,b+1+n); size=unique(b+1,b+1+n)-b-1; //求不相同的数有几个 } int Hash(int x) { return lower_bound(b+1,b+1+size,x)-b; //找到x在排好序的序列中出现的位置，即离散化后的值 } int main() { while (scanf("%d%d",&n,&m)==2) { for (int i=1;i<=n;i++) scanf("%d",&v[i]),b[i]=v[i]; Hash1(); t[0]=Build(1,size); for (int i=1;i<=n;i++) //建n棵线段树 t[i]=Update(t[i-1],Hash(v[i])); while (m--) { int l,r,k; scanf("%d%d%d",&l,&r,&k); printf("%d\n",b[Ask(t[l-1],t[r],k)]); } } return 0; }
#include <iostream> #include <algorithm> #include <cstdio> #include <cstring> #include <cstdlib> #include <cmath> #define maxn 10005 using namespace std; int use[maxn*10],n,m,size,tot=0,all=0,h[maxn*10],v[maxn*10],t[maxn*10]; struct chairtree { int l,r,size; }a[maxn*300]; struct question { int l,r,k; }q[maxn]; int lowbit(int x) { return x&(-x); } void Hash1() { sort(h+1,h+1+all); size=unique(h+1,h+1+all)-h-1; } int Hash(int x) { return lower_bound(h+1,h+1+size,x)-h; } int Build(int l,int r) { int now=++tot; a[now].size=0; if (l==r) return now; int m=(l+r)>>1; a[now].l=Build(l,m); a[now].r=Build(m+1,r); return now; } int Update(int root,int p,int val) { int now=++tot,tmp=now; int l=1,r=size; a[now].size=a[root].size+val; while (l<r) { int m=(l+r)>>1; if (p<=m) { a[now].l=++tot; a[now].r=a[root].r; root=a[root].l; now=a[now].l; r=m; } else { a[now].l=a[root].l; a[now].r=++tot; root=a[root].r; now=a[now].r; l=m+1; } a[now].size=a[root].size+val; } return tmp; } void Add(int x,int p,int val) { for (int i=x;i<=n;i+=lowbit(i)) //树状数组只需修改logn个 t[i]=Update(t[i],p,val); } int Getsum(int x) { int ans=0; for (int i=x;i;i-=lowbit(i)) ans+=a[a[use[i]].l].size; return ans; } int Query(int lx,int rx,int k) { int l=1,r=size; for (int i=lx-1;i;i-=lowbit(i)) use[i]=t[i]; for (int i=rx;i;i-=lowbit(i)) use[i]=t[i]; while (l<r) { int m=(l+r)>>1; int tmp=Getsum(rx)-Getsum(lx-1); if (tmp>=k) { for (int i=lx-1;i;i-=lowbit(i)) use[i]=a[use[i]].l; for (int i=rx;i;i-=lowbit(i)) use[i]=a[use[i]].l; r=m; } else { for (int i=lx-1;i;i-=lowbit(i)) use[i]=a[use[i]].r; for (int i=rx;i;i-=lowbit(i)) use[i]=a[use[i]].r; k-=tmp; l=m+1; } } return l; } int main() { scanf("%d%d",&n,&m); for (int i=1;i<=n;i++) scanf("%d",&v[i]),h[i]=v[i]; all=n; for (int i=1;i<=m;i++) { char str[10]; int l,r,k; scanf("%s",str); if (str[0]=='Q') { scanf("%d%d%d",&l,&r,&k); q[i].l=l,q[i].r=r,q[i].k=k; } else { scanf("%d%d",&r,&k); q[i].l=0,q[i].r=r,q[i].k=k; h[++all]=k; } } Hash1(); t[0]=Build(1,size); for (int i=1;i<=n;i++) t[i]=t[0]; for (int i=1;i<=n;i++) Add(i,Hash(v[i]),1); for (int i=1;i<=m;i++) { if (q[i].l) { printf("%d\n",h[Query(q[i].l,q[i].r,q[i].k)]); } else { Add(q[i].r,Hash(v[q[i].r]),-1); Add(q[i].r,Hash(q[i].k),1); v[q[i].r]=q[i].k; } } return 0; }
#include <cstdio> #include <iostream> #include <map> using namespace std; const int MX = 1e5+5; const int N = MX*20; int n,q,tot; int A[MX]; int T[N],lson[N],rson[N],sum[N]; int build(int l,int r) { int rt = tot++; sum[rt] = 0; int mid = (l+r)>>1; if(l!=r) { lson[rt] = build(l,mid); rson[rt] = build(mid+1,r); } return rt; } int update(int rt,int pos,int val) { int nrt = tot++; int tmp = nrt; int l=1,r=n; sum[nrt] = sum[rt] + val; while(l<r) { int mid = (l+r)>>1; if(pos<=mid) { lson[nrt] = tot++; rson[nrt] = rson[rt]; nrt = lson[nrt]; rt = lson[rt]; r = mid; } else { rson[nrt] = tot++; lson[nrt] = lson[rt]; nrt = rson[nrt]; rt = rson[rt]; l = mid+1; } sum[nrt] = sum[rt]+val; } return tmp; } int query(int rt,int pos) { int l= 1,r = n,ret = 0; while(pos>l) { int mid = (l+r)>>1; if(pos>mid) { l = mid+1; rt= rson[rt]; } else{ r = mid; ret += sum[rson[rt]]; rt = lson[rt]; } } return ret+sum[rt]; } int main() {freopen("in.txt","r",stdin); scanf("%d",&n); for(int i=1;i<=n;i++) scanf("%d",&A[i]); T[0] = build(1,n); map<int,int>mp; for(int i=1;i<=n;i++) { if(mp.find(A[i])==mp.end()) T[i] = update(T[i-1],i,1); else { int tmp = update(T[i-1],mp[A[i]],-1); T[i] = update(tmp,i,1); } mp[A[i]] = i; } scanf("%d",&q); while(q--) { int l,r; scanf("%d%d",&l,&r); printf("%d\n",query(T[r],l)); } return 0; }
