[SCOI2016]美味 [主席树]

​​传送门​​

我们按每一位贪心, 在主席树中找存不存在对异或有贡献的数就可以了

#include<bits/stdc++.h>
#define N 200050
using namespace std;
int read(){
  int cnt=0,f=1;char ch=0;
  while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
  while(isdigit(ch))cnt=cnt*10+(ch-'0'),ch=getchar();
  return cnt*f;
}
struct Node{int ls,rs,val;}t[N*40];
int rt[N],tot,n,m,Max,a[N];
void Build(int &x,int l,int r){
  x = ++tot; 
  if(l==r) return;
  int mid = (l+r) >> 1;
  Build(t[x].ls, l, mid);
  Build(t[x].rs, mid+1, r);
}
void Insert(int &x,int last,int l,int r,int pos){
  x = ++tot; t[x] = t[last]; t[x].val++;
  if(l==r) return;
  int mid = (l+r) >> 1;
  if(pos<=mid) Insert(t[x].ls, t[last].ls, l, mid, pos);
  else Insert(t[x].rs, t[last].rs, mid+1, r, pos);
}
int Quary(int a,int b,int l,int r,int L,int R){
  if(L<=l && r<=R) return t[a].val - t[b].val;
  int mid = (l+r) >> 1, ans = 0;
  if(L<=mid) ans += Quary(t[a].ls, t[b].ls, l, mid, L, R);
  if(R>mid) ans += Quary(t[a].rs, t[b].rs, mid+1, r, L, R);
  return ans;
}
int main(){
  n = read(), m = read();
  for(int i=1;i<=n;i++){
    a[i] = read();
    Max = max(a[i], Max);
  } Build(rt[0],0,Max);
  for(int i=1;i<=n;i++) Insert(rt[i], rt[i-1], 0, Max, a[i]);
  while(m--){
    int b = read(), x = read(), l = read(), r = read();
    int ans = 0;
    for(int i=17;i>=0;i--){
      int k = (b>>i)&1;
      int L = ans + ((k^1)<<i) - x;
      int R = L + (1<<i) - 1;
      if(L>Max) continue; 
      if(L<0) L = 0; if(R>Max) R = Max;
      if(Quary(rt[r], rt[l-1], 0, Max, L, R)) ans += ((k^1)<<i);
      else ans += (k<<i);
    } printf("%d\n",ans^b);
  } return 0;
}