首页 > 代码库 > HDU 2665 Kth number (主席树)
HDU 2665 Kth number (主席树)
题意:给定一个序列,求给定区间的第 k 小的值。
析:就是一个主席树的裸板。
代码如下:
#pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstring> #include <set> #include <queue> #include <algorithm> #include <vector> #include <map> #include <cctype> #include <cmath> #include <stack> #include <sstream> #define debug() puts("++++"); #define gcd(a, b) __gcd(a, b) #define lson l,m,rt<<1 #define rson m+1,r,rt<<1|1 #define freopenr freopen("in.txt", "r", stdin) #define freopenw freopen("out.txt", "w", stdout) using namespace std; typedef long long LL; typedef unsigned long long ULL; typedef pair<int, int> P; const int INF = 0x3f3f3f3f; const LL LNF = 1e16; const double inf = 0x3f3f3f3f3f3f; const double PI = acos(-1.0); const double eps = 1e-8; const int maxn = 100000 + 10; const int mod = 1e9 + 7; const int dr[] = {-1, 0, 1, 0}; const int dc[] = {0, 1, 0, -1}; const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"}; int n, m; const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; inline bool is_in(int r, int c){ return r >= 0 && r < n && c >= 0 && c < m; } int a[maxn], b[maxn]; int ls[maxn*20], rs[maxn*20], tot, c[maxn*20]; int root[maxn]; void build(int l, int r, int &rt){ rt = tot++; c[rt] = 0; if(l == r) return ; int m = l+r >> 1; build(l, m, ls[rt]); build(m+1, r, rs[rt]); } void update(int o, int p, int v, int l, int r, int &rt){ rt = tot++; c[rt] = c[o] + v; ls[rt] = ls[o]; rs[rt] = rs[o]; if(l == r) return ; int m = l+r >> 1; if(p <= m) update(ls[o], p, v, l, m, ls[rt]); else update(rs[o], p, v, m+1, r, rs[rt]); } int query(int o, int k, int l, int r, int rt){ if(l == r) return l; int m = l+r >> 1; int res = c[ls[rt]] - c[ls[o]]; if(res >= k) return query(ls[o], k, l, m, ls[rt]); return query(rs[o], k-res, m+1, r, rs[rt]); } int main(){ int T; cin >> T; while(T--){ scanf("%d %d", &n, &m); tot = 0; for(int i = 0; i < n; ++i){ scanf("%d", a+i); b[i] = a[i]; } sort(b, b + n); int sz = unique(b, b + n) - b; build(1, sz, root[0]); for(int i = 0; i < n; ++i){ int j = lower_bound(b, b + sz, a[i]) - b + 1; update(root[i], j, 1, 1, sz, root[i+1]); } while(m--){ int l, r, v; scanf("%d %d %d", &l, &r, &v); printf("%d\n", b[query(root[l-1], v, 1, sz, root[r])-1]); } } return 0; }
HDU 2665 Kth number (主席树)
声明:以上内容来自用户投稿及互联网公开渠道收集整理发布,本网站不拥有所有权,未作人工编辑处理,也不承担相关法律责任,若内容有误或涉及侵权可进行投诉: 投诉/举报 工作人员会在5个工作日内联系你,一经查实,本站将立刻删除涉嫌侵权内容。