C - Anu Has a Function(div2)

骗过我的水题

题意: 定义函数 f(a,b)=a∣b−bf(a, b) = a|b - bf(a,b)=a∣b−b, 现有数组aaa表示f(f(⋯f(f(a1,a2),a3),⋯an−1),an)f(f(\cdots f(f(a_1, a_2), a_3), \cdots a_{n-1}), a_n)f(f(⋯f(f(a1,a2),a3),⋯an−1),an) 现在要求你求整个式子的最大值, 并输出值最大时的a的顺序

Face

数据范围: 1≤n≤1e5,∣ai∣≤1e91\leq n\leq1e5, |a_i| \leq 1e91≤n≤1e5,∣ai∣≤1e9

Tutorial: 列个表出来:

a	b	val
0	0	0
0	1	0
1	0	1
1	1	0

你有没有发现什么?

再看这张表:

a	~b	val
0	1	0
0	0	0
1	1	1
1	0	0

也许你会spot :f(a,b)=a∣b−b=a&(f(a, b) = a|b - b = a\&(f(a,b)=a∣b−b=a&(~b)b)b)

于是整个式子就变成了 a1&(a_1\&(a1&(~a2)&(a_2 )\&(a2)&(~a3)…a_3)\ldotsa3)…
求这个式子最大值显然就只与第一个元素有关了, 于是可以用前后缀和维护

#include <bits/stdc++.h>
#include <bits/extc++.h>using namespace std;
#define _rep(n, a, b) for (ll n = (a); n <= (b); ++n)
#define _rev(n, a, b) for (ll n = (a); n >= (b); --n)
#define _for(n, a, b) for (ll n = (a); n < (b); ++n)
#define _rof(n, a, b) for (ll n = (a); n > (b); --n)
#define oo 0x3f3f3f3f3f3f
#define ll long long
#define db double
#define eps 1e-8
#define bin(x) cout << bitset<10>(x) << endl;
#define what_is(x) cerr << #x << " is " << x << endl
#define met(a, b) memset(a, b, sizeof(a))
#define all(x) x.begin(), x.end()
#define pii pair<ll, ll>
#define pdd pair<db, db>
const ll mod = 1e9 + 7;
const ll maxn = 1e5 + 10;
#define lowbit(x) x &(-x)
ll pre[maxn], suf[maxn];
vector<ll> a;
ll n;
ll ask(int i) {if (i == 1)return a[1] & suf[2];if (i == n)return pre[n - 1] & a[i];return pre[i - 1] & a[i] & suf[i + 1];
}
signed main()
{cin >> n;a.resize(n + 1);ll fir_id = 1;_rep(i, 1, n) {cin >> a[i];if (i == 1)pre[0] = ~a[i];if (i == n) suf[n + 1] = ~a[i];pre[i] = pre[i - 1] & (~a[i]);}_rev(i, n, 1) {suf[i] = suf[i + 1] & (~a[i]);}_rep(i, 2, n) {if(ask(fir_id) < ask(i)) {fir_id = i;}}cout << a[fir_id] << " ";_rep(i, 1, n) {if (i != fir_id) {cout << a[i] << " ";}}}

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C - Anu Has a Function(div2)

骗过我的水题

题意: 定义函数 f(a,b)=a∣b−bf(a, b) = a|b - bf(a,b)=a∣b−b, 现有数组aaa表示f(f(⋯f(f(a1,a2),a3),⋯an−1),an)f(f(\cdots f(f(a_1, a_2), a_3), \cdots a_{n-1}), a_n)f(f(⋯f(f(a1,a2),a3),⋯an−1),an) 现在要求你求整个式子的最大值, 并输出值最大时的a的顺序

数据范围: 1≤n≤1e5,∣ai∣≤1e91\leq n\leq1e5, |a_i| \leq 1e91≤n≤1e5,∣ai∣≤1e9

Tutorial: 列个表出来:

C - Anu Has a Function(div2)相关推荐

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热门文章

C - Anu Has a Function(div2)

骗过我的水题

数据范围: 1≤n≤1e5,∣ai∣≤1e91\leq n\leq1e5, |a_i| \leq 1e91≤n≤1e5,∣ai​∣≤1e9

Tutorial: 列个表出来:

C - Anu Has a Function(div2)相关推荐

最新文章

热门文章

数据范围: 1≤n≤1e5,∣ai∣≤1e91\leq n\leq1e5, |a_i| \leq 1e91≤n≤1e5,∣ai∣≤1e9