2022杭电杯超级联赛09

1010-Sum Plus Product

来源: 杭电杯超级联赛9 算法: 数论, 语法 题目链接: https://acm.dingbacode.com/contest/problem?cid=1052&pid=1010 补完: Yes 完成时间: August 16, 2022

题解

以球\(a,b,c\)为例推演发现, 不论谁先组合都有答案\(a+b+c+ab+ac+bc+abc\).

总体计算答案时可视为若干球依次放入\(ans +=new+new\cdot ans\)

代码

#include<bits/stdc++.h>

using namespace std;

#define ll long long

const ll P = 998244353;
const int MAXN = 505;

ll a[MAXN];

ll add(ll a, ll b){
    return (a+b)%P;
}

ll mul(ll a, ll b){
    return (a*b)%P;
}
void solve() {
    int n;
    cin>>n;
    for (int i = 1; i <= n; i++) {
        cin>>a[i];
    }
    ll ans = 0;
    for (int i = 1; i <= n; i++) {
        ans = add(ans,add(a[i],mul(ans,a[i])));
    }
    cout<<ans<<"\n";
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int T = 1;
    cin>>T;
    while (T--) {
        solve();
    }
    return 0;
}