[POJ](2309)BST ---- 树状数组lowbit

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题目传送门

做法：其实还是从题目中给的这棵二叉搜索树找规律，我们发现最小的其实就是 x-lowbit(x)+1，即树状数组中x位置所维护的区间的左端点，接机推出最大即x+lowbit(x)-1;

AC代码：

#include <iostream>
#include <cmath>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#include <ctime>
#define IO          ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0)
#define pb(x)       push_back(x)
#define sz(x)       (int)(x).size()
#define sc(x)       scanf("%d",&x)
#define pr(x)       printf("%d\n",x)
#define abs(x)      ((x)<0?-(x):x)
#define all(x)      x.begin(),x.end()
using namespace std;
typedef long long ll;
const int mod = 1e9+7;
const double PI = 4*atan(1.0);
const int maxm = 1e8+5;
const int maxn = 1e5+5;
const int INF = 0x3f3f3f3f;
inline int lowbit(int x){return x&(-x);}
int main()
{
    #ifdef LOCAL_FILE
    freopen("in.txt","r",stdin);
    #endif // LOCAL_FILE
    IO;
    int n;
    cin>>n;
    while(n--)
    {
        int i;
        cin>>i;
        cout<<i-lowbit(i)+1<<" "<<i+lowbit(i)-1<<endl;//
    }
    #ifdef LOCAL_FILE
    cout << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC * 1000 << "ms." << endl;
    #endif // LOCAL_FILE
    return 0;
}