[POJ2761]Feed the dogs（静态区间第k小，主席树）

Posted 2020-08-06

题目链接：http://poj.org/problem?id=2761

题意：如题

主席树只能用模版，好菜。

  1 /*
  2 ━━━━━┒ギリギリ♂ eye！
  3 ┓┏┓┏┓┃キリキリ♂ mind！
  4 ┛┗┛┗┛┃＼○／
  5 ┓┏┓┏┓┃ /
  6 ┛┗┛┗┛┃ノ)
  7 ┓┏┓┏┓┃
  8 ┛┗┛┗┛┃
  9 ┓┏┓┏┓┃
 10 ┛┗┛┗┛┃
 11 ┓┏┓┏┓┃
 12 ┛┗┛┗┛┃
 13 ┓┏┓┏┓┃
 14 ┃┃┃┃┃┃
 15 ┻┻┻┻┻┻
 16 */
 17 #include <algorithm>
 18 #include <iostream>
 19 #include <iomanip>
 20 #include <cstring>
 21 #include <climits>
 22 #include <complex>
 23 #include <fstream>
 24 #include <cassert>
 25 #include <cstdio>
 26 #include <bitset>
 27 #include <vector>
 28 #include <deque>
 29 #include <queue>
 30 #include <stack>
 31 #include <ctime>
 32 #include <set>
 33 #include <map>
 34 #include <cmath>
 35 using namespace std;
 36 #define fr first
 37 #define sc second
 38 #define cl clear
 39 #define BUG puts("here!!!")
 40 #define W(a) while(a--)
 41 #define pb(a) push_back(a)
 42 #define Rint(a) scanf("%d", &a)
 43 #define Rll(a) scanf("%I64d", &a)
 44 #define Rs(a) scanf("%s", a)
 45 #define Cin(a) cin >> a
 46 #define FRead() freopen("in", "r", stdin)
 47 #define FWrite() freopen("out", "w", stdout)
 48 #define Rep(i, len) for(int i = 0; i < (len); i++)
 49 #define For(i, a, len) for(int i = (a); i < (len); i++)
 50 #define Cls(a) memset((a), 0, sizeof(a))
 51 #define Clr(a, x) memset((a), (x), sizeof(a))
 52 #define Full(a) memset((a), 0x7f7f7f, sizeof(a))
 53 #define lrt rt << 1
 54 #define rrt rt << 1 | 1
 55 #define pi 3.14159265359
 56 #define RT return
 57 #define lowbit(x) x & (-x)
 58 #define onecnt(x) __builtin_popcount(x)
 59 typedef long long LL;
 60 typedef long double LD;
 61 typedef unsigned long long ULL;
 62 typedef pair<int, int> pii;
 63 typedef pair<string, int> psi;
 64 typedef pair<LL, LL> pll;
 65 typedef map<string, int> msi;
 66 typedef vector<int> vi;
 67 typedef vector<LL> vl;
 68 typedef vector<vl> vvl;
 69 typedef vector<bool> vb;
 70 
 71 const int maxn = 1000010;
 72 int n, m;
 73 int cnt, root[maxn], a[maxn], x, y, k;
 74 typedef struct Node {
 75     int l, r, sum;
 76 }Node;
 77 vector<int> h;
 78 Node tree[maxn*40];
 79 
 80 int getid(int x) {
 81     return lower_bound(h.begin(), h.end(), x) - h.begin() + 1;
 82 }
 83 
 84 void update(int l, int r, int pre, int& cur, int pos) {
 85     tree[++cnt] = tree[pre], tree[cnt].sum++, cur = cnt;
 86     if(l == r) return;
 87     int mid = (l + r) >> 1;
 88     if(mid >= pos) update(l, mid, tree[pre].l, tree[cur].l, pos);
 89     else update(mid+1, r, tree[pre].r, tree[cur].r, pos);
 90 }
 91 
 92 int query(int l, int r, int x, int y, int k) {
 93     if(l == r) return l;
 94     int mid = (l + r) >> 1;
 95     int sum = tree[tree[y].l].sum - tree[tree[x].l].sum;
 96     if(sum >= k) return query(l, mid, tree[x].l, tree[y].l, k);
 97     else return query(mid+1, r, tree[x].r, tree[y].r, k-sum);
 98 }
 99 
100 int main() {
101     // FRead();
102     Rint(n); Rint(m);
103     For(i, 1, n+1) {
104         Rint(a[i]);
105         h.pb(a[i]);
106     }
107     sort(h.begin(), h.end()), h.erase(unique(h.begin(), h.end()), h.end());
108     For(i, 1, n+1) update(1, n, root[i-1], root[i], getid(a[i]));
109     For(i, 1, m+1) {
110         Rint(x), Rint(y), Rint(k);
111         printf("%d\n", h[query(1, n, root[x-1], root[y], k)-1]);
112     }
113     return 0;
114 }

 

/*━━━━━┒ギリギリ♂ eye！┓┏┓┏┓┃キリキリ♂ mind！┛┗┛┗┛┃＼○／┓┏┓┏┓┃ /┛┗┛┗┛┃ノ)┓┏┓┏┓┃┛┗┛┗┛┃┓┏┓┏┓┃┛┗┛┗┛┃┓┏┓┏┓┃┛┗┛┗┛┃┓┏┓┏┓┃┃┃┃┃┃┃┻┻┻┻┻┻*/#include <algorithm>#include <iostream>#include <iomanip>#include <cstring>#include <climits>#include <complex>#include <fstream>#include <cassert>#include <cstdio>#include <bitset>#include <vector>#include <deque>#include <queue>#include <stack>#include <ctime>#include <set>#include <map>#include <cmath>using namespace std;#define fr first#define sc second#define cl clear#define BUG puts("here!!!")#define W(a) while(a--)#define pb(a) push_back(a)#define Rint(a) scanf("%d", &a)#define Rll(a) scanf("%I64d", &a)#define Rs(a) scanf("%s", a)#define Cin(a) cin >> a#define FRead() freopen("in", "r", stdin)#define FWrite() freopen("out", "w", stdout)#define Rep(i, len) for(int i = 0; i < (len); i++)#define For(i, a, len) for(int i = (a); i < (len); i++)#define Cls(a) memset((a), 0, sizeof(a))#define Clr(a, x) memset((a), (x), sizeof(a))#define Full(a) memset((a), 0x7f7f7f, sizeof(a))#define lrt rt << 1#define rrt rt << 1 | 1#define pi 3.14159265359#define RT return#define lowbit(x) x & (-x)#define onecnt(x) __builtin_popcount(x)typedef long long LL;typedef long double LD;typedef unsigned long long ULL;typedef pair<int, int> pii;typedef pair<string, int> psi;typedef pair<LL, LL> pll;typedef map<string, int> msi;typedef vector<int> vi;typedef vector<LL> vl;typedef vector<vl> vvl;typedef vector<bool> vb;
const int maxn = 1000010;int n, m;int cnt, root[maxn], a[maxn], x, y, k;typedef struct Node {int l, r, sum;}Node;vector<int> h;Node tree[maxn*40];
int getid(int x) {return lower_bound(h.begin(), h.end(), x) - h.begin() + 1;}
void update(int l, int r, int pre, int& cur, int pos) {tree[++cnt] = tree[pre], tree[cnt].sum++, cur = cnt;if(l == r) return;int mid = (l + r) >> 1;if(mid >= pos) update(l, mid, tree[pre].l, tree[cur].l, pos);else update(mid+1, r, tree[pre].r, tree[cur].r, pos);}
int query(int l, int r, int x, int y, int k) {if(l == r) return l;int mid = (l + r) >> 1;int sum = tree[tree[y].l].sum - tree[tree[x].l].sum;if(sum >= k) return query(l, mid, tree[x].l, tree[y].l, k);else return query(mid+1, r, tree[x].r, tree[y].r, k-sum);}
int main() {// FRead();Rint(n); Rint(m);For(i, 1, n+1) {Rint(a[i]);h.pb(a[i]);}sort(h.begin(), h.end()), h.erase(unique(h.begin(), h.end()), h.end());For(i, 1, n+1) update(1, n, root[i-1], root[i], getid(a[i]));For(i, 1, m+1) {Rint(x), Rint(y), Rint(k);printf("%d\n", h[query(1, n, root[x-1], root[y], k)-1]);}return 0;}