K-th Number
区间第K大
1 #include <stdio.h> 2 #include <algorithm> 3 #include <vector> 4 #include <iostream> 5 using namespace std; 6 typedef long long ll; 7 inline int read() 8 { 9 int x=0,f=1;char ch=getchar(); 10 while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} 11 while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} 12 return x*f; 13 } 14 15 /********************************************************************/ 16 17 const int maxn = 1e5+7; 18 int n, m, cnt, root[maxn], a[maxn], x, y, k; 19 20 struct node{ 21 int l, r, sum; 22 }T[maxn*40]; 23 24 vector<int>v; 25 int getid(int x){return lower_bound(v.begin(), v.end(), x) - v.begin() + 1;} //离散化 26 27 void update(int l, int r, int &x, int y, int pos){ 28 T[++cnt] = T[y], T[cnt].sum++, x = cnt; 29 if(l == r) return ; 30 int mid = (l+r)>>1; 31 if(mid >= pos) update(l, mid, T[x].l, T[y].l, pos); 32 else update(mid+1, r, T[x].r, T[y].r, pos); 33 } 34 35 int query(int l, int r, int x, int y, int k){ 36 if(l == r) return l; 37 int mid = (l+r)>>1; 38 int sum = T[T[y].l].sum - T[T[x].l].sum; 39 if(sum >= k) return query(l, mid, T[x].l, T[y].l, k); 40 else return query(mid+1, r, T[x].r, T[y].r, k-sum); 41 } 42 43 int main(){ 44 n = read(); m = read(); 45 for(int i = 1;i <= n;i++){ 46 a[i] = read(); 47 v.push_back(a[i]); 48 } 49 //离散化 50 sort(v.begin(), v.end()); 51 v.erase(unique(v.begin(), v.end()), v.end()); 52 //unique 去重 53 for(int i = 1;i <= n;i++) update(1, n, root[i], root[i-1], getid(a[i])); 54 for(int i = 1;i <= m;i++){ 55 x = read(); y = read(); k = read(); 56 printf("%d\n", v[query(1, n, root[x-1], root[y], k) - 1]); //离散化回来 57 } 58 return 0; 59 }
