提出 #67555430

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ソースコード 拡げる

#include<bits/stdc++.h>
using namespace std;
#define IOS ios_base::sync_with_stdio(false);cin.tie(nullptr)
#define INF 0x7fffffff
#define inf 0x3f3f3f3f
#define endl '\n'
#define int long long
#define PII pair<int,int>
const int MOD=998244353;
const int N=1e5+10;
int read() {char act = 0;int f = 1, x= 0;while (act = getchar(), act < '0' && act != '-');if (act == '-') f = -1, act = getchar();x = act - '0';while (act = getchar(), act >= '0') x = x * 10 + act - '0';return x * f;}
int mul_mod(int a, int b) {
    return (__int128)a * b % MOD;
}
int pow_mod(int x, int y = MOD - 2) {
    int res = 1;
    while (y) {
        if (y & 1) res = mul_mod(res, x);
        x = mul_mod(x, x);
        y >>= 1;
    }
    return res;
}
void solve(){
    int N;
    cin >> N;
    const int inv2 = (MOD + 1) / 2;
    int H = 0;
    int i = 1;
    while (i <= N) {
        int q = N / i;
        int last = N / q;
        int cnt = (last - i + 1) % MOD;
        H = (H + mul_mod(q % MOD, cnt)) % MOD;
        i = last + 1;
    }
    int T = mul_mod(N % MOD, (N + 1) % MOD);
    T = mul_mod(T, inv2);
    int ans = (T - H) % MOD;
    if (ans < 0) ans += MOD;
    cout << ans << endl;
}
signed main()
{
    IOS;
    int t=1;
    //cin>>t;
    while(t--){
        solve();
    }

    return 0;
}

提出情報

ジャッジ結果