[AcWing 241] 楼兰图腾
作者:互联网
树状数组 复杂度 \(n \cdot log(n)\)
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#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N = 2e5 + 10;
int n;
int a[N];
int tr[N];
int g[N], l[N];
int lowbit(int x)
{
return x & -x;
}
void add(int x, int c)
{
for (int i = x; i <= n; i += lowbit(i))
tr[i] += c;
}
int ask(int x)
{
int res = 0;
for (int i = x; i; i -= lowbit(i))
res += tr[i];
return res;
}
void solve()
{
cin >> n;
for (int i = 1; i <= n; i ++)
cin >> a[i];
for (int i = 1; i <= n; i ++) {
int y = a[i];
g[i] = ask(n) - ask(y);
l[i] = ask(y - 1);
add(y, 1);
}
memset(tr, 0, sizeof tr);
LL res1 = 0, res2 = 0;
for (int i = n; i; i --) {
int y = a[i];
res1 += g[i] * 1LL * (ask(n) - ask(y));
res2 += l[i] * 1LL * (ask(y - 1));
add(y, 1);
}
cout << res1 << ' ' << res2 << endl;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
solve();
return 0;
}
- 对于 "V" 型,使用树状数组维护 \(y_i\) 左边和右边比 \(y_i\) 大的数的个数,另一种形状类似,使用树状数组维护 \(y_i\) 左边和右边比 \(y_i\) 小的数的个数
标签:右边,楼兰,树状,int,个数,long,241,数组,AcWing 来源: https://www.cnblogs.com/wKingYu/p/16495730.html