ZOJ 2112:Dynamic Rankings(主席树查询区间第k小(带修改))

题目和算法在上一篇讲了，这篇用来贴代码:

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e5+10;
const int maxm = 2000010;
#define lowbit(i) (i & (-i))
int n,m,q,p,t,tot,a[maxn],tt[maxn],use[maxn];
struct ss{
 	int l,r,val;
}tree[maxm];
struct qq{
 	int id,x,y,z;
}qes[10010];
int root[maxn],s[maxn],cnt;
int init_hash(){
 	for(int i = 1; i <= n; i++) tt[i] = a[i];
 	sort(tt + 1,tt + tot + 1);
 	int p = unique(tt + 1,tt + tot + 1) - tt - 1;
 	return p;
}
int Hash(int key){
 	int d = lower_bound(tt + 1,tt + p + 1,key) - tt;
 	return d;
}
void init(){
 	memset(root,0,sizeof(root));
 	memset(s,0,sizeof(s));
 	tree[0].l = tree[0].r = tree[0].val = 0;
 	cnt = tot = 0;
}
void update(int &rt,int l,int r,int k,int v){
 	tree[++cnt] = tree[rt];
 	rt = cnt;
 	tree[rt].val += v;
 	if(l == r) return;
 	int mid = l + r >> 1;
 	if(k > mid) update(tree[rt].r,mid + 1,r,k,v);
 	else update(tree[rt].l,l,mid,k,v);
}
void modify(int pos,int k,int v){
 	for(int i = pos; i <= n; i += lowbit(i))
 	update(s[i],1,p,k,v);
}
void get(int L,int R,int f){
 	for(int i = R; i >= 1; i -= lowbit(i)){
  		if(f == 1) use[i] = tree[use[i]].l;
  		else use[i] = tree[use[i]].r;
 	}
 	for(int i = L; i >= 1; i -= lowbit(i)){
  		if(f == 1) use[i] = tree[use[i]].l;
  		else use[i] = tree[use[i]].r;
 	}  
}
int ask(int L,int R){
 	int res = 0,child;
 	for(int i = R; i >= 1; i -= lowbit(i)){
  		child = tree[use[i]].l;
  		res += tree[child].val;
 	}
 	for(int i = L; i >= 1; i -= lowbit(i)){
  		child = tree[use[i]].l;
  		res -= tree[child].val;
 	}
 	return res;
}
int query(int L,int R,int k){
 	int l = 1,r = p;
 	int i = root[L],j = root[R];
 	for(int i = R; i >= 1; i -= lowbit(i)) use[i] = s[i];
 	for(int i = L; i >= 1; i -= lowbit(i)) use[i] = s[i];
 	while(l < r){
  		int mid = l + r >> 1;
  		int sz = ask(L,R) + tree[tree[j].l].val - tree[tree[i].l].val;
  		if(sz >= k){   //同时移动到左子树 
  			get(L,R,1);
   			i = tree[i].l;
   			j = tree[j].l;
   			r = mid;
  		}
  		else{
   			k -= sz;
   			get(L,R,0);
   			i = tree[i].r;
   			j = tree[j].r;
   			l = mid + 1;
  		}
 	}
 	return l;
}
char op[2];
int main(){
 	int x,y,z;
 	scanf("%d",&t);
 	while(t--){
  		scanf("%d%d",&n,&m);
  		init();
  		tot = n;
  		for(int i = 1; i <= n; i++){
  		 	scanf("%d",&a[i]);
  		}
  		for(int i = 1; i <= m; i++){
   			scanf("%s",op);
   			if(op[0] == 'Q'){
    				qes[i].id = 0;
    				scanf("%d%d%d",&qes[i].x,&qes[i].y,&qes[i].z);
   			} 	
   			else{
    				qes[i].id = 1;
    				scanf("%d%d",&qes[i].x,&qes[i].y);
    				tt[++tot] = qes[i].y;
    			}
  		}	 
  		p = init_hash();
  		for(int i = 1; i <= n; i++){
   			int mp = Hash(a[i]);
   			root[i] = root[i - 1];
   			update(root[i],1,p,mp,1);
  		}
  		for(int i = 1; i <= m; i++){
   			if(qes[i].id == 0){
    				printf("%d\n",tt[query(qes[i].x - 1,qes[i].y,qes[i].z)]);
   			}
   			else{
    				modify(qes[i].x,Hash(a[qes[i].x]),-1);
    				modify(qes[i].x,Hash(qes[i].y),1);
    				a[qes[i].x] = qes[i].y;
   			}
  		}
 	}
 	return 0;
}

递归(略麻烦的是那个查询左子树右子树这个操作，要操作log(n)棵树)

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e5+10;
const int maxm = 2000010;
#define lowbit(i) (i & (-i))
int n,m,q,p,t,tot,a[maxn],tt[maxn],use[maxn];
struct ss{
	int l,r,val;
}tree[maxm];
struct qq{
	int id,x,y,z;
}qes[10010];
int root[maxn],s[maxn],cnt;

int init_hash(){
	for(int i = 1; i <= n; i++) tt[i] = a[i];
	sort(tt + 1,tt + tot + 1);
	int p = unique(tt + 1,tt + tot + 1) - tt - 1;
	return p;
}
int Hash(int key){
	int d = lower_bound(tt + 1,tt + p + 1,key) - tt;
	return d;
}
void init(){
	memset(root,0,sizeof(root));
	memset(s,0,sizeof(s));
	tree[0].l = tree[0].r = tree[0].val = 0;
	cnt = tot = 0;
}
void update(int &rt,int l,int r,int k,int v){
	tree[++cnt] = tree[rt];
	rt = cnt;
	tree[rt].val += v;
	if(l == r) return;
	int mid = l + r >> 1;
	if(k > mid) update(tree[rt].r,mid + 1,r,k,v);
	else update(tree[rt].l,l,mid,k,v);
}
void modify(int pos,int k,int v){
	for(int i = pos; i <= n; i += lowbit(i))
		update(s[i],1,p,k,v);
}
void get(int L,int R,int f){
	for(int i = R; i >= 1; i -= lowbit(i)){
		if(f == 1) use[i] = tree[use[i]].l;
		else use[i] = tree[use[i]].r;
	}
	for(int i = L; i >= 1; i -= lowbit(i)){
		if(f == 1) use[i] = tree[use[i]].l;
		else use[i] = tree[use[i]].r;
	} 	
}
int ask(int L,int R,int f){
	int res = 0,child;
	for(int i = R; i >= 1; i -= lowbit(i)){
		child = tree[use[i]].l;
		res += tree[child].val;
	}
	for(int i = L; i >= 1; i -= lowbit(i)){
		child = tree[use[i]].l;
		res -= tree[child].val;
	}
	return res;
}
int query(int ls,int rs,int L,int R,int l,int r,int k){
	if(l == r){
		return l;
	}
	int mid = l + r >> 1;
	int cur = ask(L,R,1) + tree[tree[rs].l].val - tree[tree[ls].l].val;
	if(cur >= k){
		get(L,R,1);
		return query(tree[ls].l,tree[rs].l,L,R,l,mid,k);
	}
	else{
		get(L,R,0);
		return query(tree[ls].r,tree[rs].r,L,R,mid + 1,r,k - cur);
	}
}
int Answer(int L,int R,int l,int r,int k){
	for(int i = R; i >= 1; i -= lowbit(i)) use[i] = s[i];
	for(int i = L; i >= 1; i -= lowbit(i)) use[i] = s[i];
	return query(root[L],root[R],L,R,l,r,k);
}
char op[2];
int main(){
	int x,y,z;
	scanf("%d",&t);
	while(t--){
		scanf("%d%d",&n,&m);
		init();
		tot = n;
		for(int i = 1; i <= n; i++){
			scanf("%d",&a[i]);
		}
		for(int i = 1; i <= m; i++){
			scanf("%s",op);
			if(op[0] == 'Q'){
				qes[i].id = 0;
				scanf("%d%d%d",&qes[i].x,&qes[i].y,&qes[i].z);
			}	
			else{
				qes[i].id = 1;
				scanf("%d%d",&qes[i].x,&qes[i].y);
				tt[++tot] = qes[i].y;
 			}
		}	
		p = init_hash();
		for(int i = 1; i <= n; i++){
			int mp = Hash(a[i]);
			root[i] = root[i - 1];
			update(root[i],1,p,mp,1);
		}
		for(int i = 1; i <= m; i++){
			if(qes[i].id == 0){
				printf("%d\n",tt[Answer(qes[i].x - 1,qes[i].y,1,p,qes[i].z)]);
			}
			else{
				modify(qes[i].x,Hash(a[qes[i].x]),-1);
				modify(qes[i].x,Hash(qes[i].y),1);
				a[qes[i].x] = qes[i].y;
			}
		}
	}
	return 0;
}