HDU 5412 CRB and Queries(整体二分 | CDQ分治)

题意：

给定一个数列，有两种操作，单点修改和区间第k大值。

分析：

整体二分的裸题吧算是，整体二分和CDQ分治还是有点不同的，主要是他还把答案二分出来了，每次判定的时候都会把答案往他应该去的地方放，到了最后就是要查询的答案了，讲的话太复杂，还是看代码理解吧

代码：

//
//  Created by  CQU_CST_WuErli
//  Copyright (c) 2016 CQU_CST_WuErli. All rights reserved.
//
//#pragma comment(linker, "/STACK:102400000,102400000")
#include <iostream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <string>
#include <vector>
#include <map>
#include <queue>
#include <stack>
#include <set>
#include <algorithm>
#include <sstream>
#include <bitset>
#define CLR(x) memset(x,0,sizeof(x))
#define OFF(x) memset(x,-1,sizeof(x))
#define MEM(x,a) memset((x),(a),sizeof(x))
#define BUG cout << "I am here" << endl
#define lookln(x) cout << #x << "=" << x << endl
#define SI(a) scanf("%d", &a)
#define SII(a,b) scanf("%d%d", &a, &b)
#define SIII(a,b,c) scanf("%d%d%d", &a, &b, &c)
const int INF_INT=0x3f3f3f3f;
const long long INF_LL=0x7f7f7f7f;
const int MOD=1e9+7;
const double eps=1e-10;
const double pi=acos(-1);
typedef long long  ll;
using namespace std;

const int N = 4e5 + 100;

struct Bit {
int sum
;
int n;
int lowbit(int x) {
return x & (-x);
}
void init(int _n) {
n = _n;
CLR(sum);
}
void update(int pos, int val) {
while (pos <= n) {
sum[pos] += val;
pos += lowbit(pos);
}
}
int query(int pos) {
int ret = 0;
while (pos) {
ret += sum[pos];
pos -= lowbit(pos);
}
return ret;
}
}bit;

struct Q {
int id, l, r, k;
Q() {}
Q(int id, int l, int r, int k):id(id), l(l), r(r), k(k) {}
};
Q q
, q1
, q2
;
int n, m;
int val
, mp
;
int ans
;
int tid;

void cdq(int qL, int qR, int l, int r) {
if (qL > qR) return;
if (l == r) {
for (int i = qL; i <= qR; i++) {
if (q[i].id) {
ans[q[i].id] = mp[l];
}
}
return;
}
// cout << l << ' ' <<r << endl;
int mid = l + r >> 1;
int cnt1 = 0, cnt2 = 0;
for (int i = qL; i <= qR; i++) {
if (q[i].id == 0) {
if (q[i].k <= mid) {
bit.update(q[i].l, q[i].r);
q1[++cnt1] = q[i];
}
else q2[++cnt2] = q[i];
}
else {
int rnk = bit.query(q[i].r) - bit.query(q[i].l - 1);
if (q[i].k <= rnk) {
q1[++cnt1] = q[i];
}
else {
q[i].k -= rnk;
q2[++cnt2] = q[i];
}
}
}
for (int i = 1; i <= cnt1; i++) {
if (q1[i].id == 0)
bit.update(q1[i].l, -q1[i].r);
}
for (int i = 1; i <= cnt1; i++)
q[qL + i - 1] = q1[i];
for (int i = 1; i <= cnt2; i++)
q[qL + cnt1 - 1 + i] = q2[i];
cdq(qL, qL + cnt1 - 1, l, mid);
cdq(qL + cnt1, qR, mid + 1, r);
}

int main(int argc, char const *argv[]) {
#ifdef LOCAL
freopen("C:\\Users\\john\\Desktop\\in.txt","r",stdin);
// freopen("C:\\Users\\john\\Desktop\\out.txt","w",stdout);
#endif
while (SI(n) == 1) {
int qcnt = 0, cnt = 0;
tid = 0;
for (int i = 1; i <= n; i++) {
SI(val[i]);
q[++qcnt] = Q(0, i, 1, val[i]);
mp[++cnt] = val[i];
}
SI(m);
for (int i = 1,op, l, r, k; i <= m; i++) {
SI(op);
if (op == 1) {
SII(l, k);
q[++qcnt] = Q(0, l, -1, val[l]);
q[++qcnt] = Q(0, l, 1, k);
mp[++cnt] = k;
val[l] = k;
}
else {
SIII(l, r, k);
q[++qcnt] = Q(++tid, l, r, k);
}
}
sort(mp + 1, mp + 1 + cnt);
cnt = unique(mp + 1, mp + 1 + cnt) - mp - 1;
for (int i = 1; i <= qcnt; i++) {
if (q[i].id == 0) {
q[i].k = lower_bound(mp + 1, mp + 1 + cnt, q[i].k) - mp;
}
}
bit.init(n);
cdq(1, qcnt, 1, cnt);
for (int i = 1; i <= tid; i++)
printf("%d\n", ans[i]);
}
return 0;
}