题解 | 有趣的区间

一个比较经典的题目，思路详情可看：【1月17日 牛客每日一题】

#include <bits/stdc++.h>
#define il inline
#define double long double
using namespace std;
using ll = long long;
using ull = unsigned long long;
using int128 = __int128_t;

const ll N = 2e5 + 5, mod = 1e9+7, inf = 2e18;
const double eps = 1e-9;
double PI = 3.1415926;

il void solve(){
    int n;
    cin>>n;
    ll ans=0,idx=0;
    for(int i=1;i<=n;i++){
        int x;
        cin>>x;
        if(x&1){
            ans+=i;
            idx=i;
        }else{
            ans+=idx;
        }
    }
    cout<<ans;
}

int main(){
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    int t = 1;

    // cin >> t;

    while (t--){

        solve();
    }

    return 0;
}