牛客练习赛7 E 珂朵莉的数列(树状数组+爆long long解决方法)

https://www.nowcoder.com/acm/contest/38/E

题意:

牛客练习赛7 E	珂朵莉的数列(树状数组+爆long long解决方法)

思路:

树状数组维护。从大佬那里学习了如何处理爆long long的方法。

 #include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
const int maxn = +; int n;
int a[maxn],b[maxn];
ll c[maxn]; int lowbit(int x)
{
return x&(-x);
} void add(int x ,int d)
{
while(x<maxn)
{
c[x] += d;
x += lowbit(x);
}
} ll sum(int x)
{
ll ret = ;
while(x>)
{
ret += c[x];
x -= lowbit(x);
}
return ret;
} int main()
{
//freopen("in.txt","r",stdin);
scanf("%d",&n);
for(int i=;i<=n;i++)
{
scanf("%d",&a[i]);
b[i] = a[i];
}
sort(b+,b+n+);
int num = unique(b+,b+n+)-(b+);
ll ans1 = , ans2 = ;
ll mx = 1e18;
for(int i=;i<=n;i++)
{
a[i] = lower_bound(b+,b+n+,a[i])-(b+);
a[i]++;
ans1 += (ll)(n-i+)*(sum(n)-sum(a[i]));
if(ans1>=mx) ans2 += ans1/mx, ans1%=mx;
add(a[i],i);
}
if(ans2) printf("%lld%018lld\n",ans2,ans1);
else printf("%lld\n",ans1);
return ;
}
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