30 lines
811 B
C++
30 lines
811 B
C++
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#include <iostream>
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using namespace std;
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long long alpha[500005], beta[500005];
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long long pre_alpha[500005], pre_beta[500005];
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long long sum_alpha, sum_beta;
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long long ans;
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const int mod = 1000000007;
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int main() {
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int n;
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cin >> n;
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for (int i = 1; i <= n; ++i) {
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cin >> alpha[i];
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pre_alpha[i] = (pre_alpha[i - 1] + alpha[i]) % mod;
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}
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for (int i = 1; i <= n; ++i) {
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cin >> beta[i];
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pre_beta[i] = (pre_beta[i - 1] + beta[i]) % mod;
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}
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for (int i = 1; i <= n; i++) {
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(ans += (((n + 1) * pre_alpha[i]) % mod) * pre_beta[i]) %= mod;
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sum_alpha = (sum_alpha + pre_alpha[i]) % mod;
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sum_beta = (sum_beta + pre_beta[i]) % mod;
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}
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long long tot = (sum_alpha * sum_beta) % mod;
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ans = (ans - tot + mod) % mod;
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cout << ans;
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}
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