第37次CCF计算机软件能力认证 / T4 / 集体锻炼

题目

代码

#include <bits/stdc++.h>
using namespace std;
using LL = long long;

const int N = 1e6 + 10;
const int mod = 998244353;
int a[N];
int st[N][22];

int get(int l, int r)
{
    int x = r - l + 1;
    int k = log2(x);
    return __gcd(st[l][k], st[r - (1 << k) + 1][k]);
}
int main()
{
    int n;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)
        scanf("%d", &a[i]);

    for (int i = 1; i <= n; i++)
        st[i][0] = a[i];
    for (int j = 1; j <= 20; j++)
        for (int i = 1; i + 1 << j <= n; i++)
        {
            st[i][j] = __gcd(st[i][j - 1], st[i + 1 << j - 1][j - 1]);
        }

    LL ans = 0;
    for (int l = 1; l <= n; l++)
    {
        int r = l;
        int x = a[l];

        while (r <= n)
        {
            int ll = r;
            int rr = n;

            while (ll < rr)
            {
                int mid = ll + rr + 1 >> 1;
                if (get(l, mid) == x)
                    ll = mid;
                else
                    rr = mid - 1;
            }

            LL rsum;
            rsum = 1ll * (r + rr) * (rr - r + 1) / 2;
            ans = (ans + 1ll * l * rsum % mod * x % mod) % mod;
            r = rr + 1;
            if (r <= n)
                x = __gcd(x, a[r]);
        }
    }
 
    printf("%lld", ans);
}