AtCoder · abc439_a
This C++ solution uses simulation for AtCoder abc439_a A - 2^n - 2*n. Read the reasoning, inspect the code, or try your own test case below.
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Approach
title is 2^n - 2*n; its single N input and required formula match the code.
Problem and code
Written by benbenyaojifen. Try the problem first, then compare your approach with the code.
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
ios::sync_with_stdio(0); cin.tie(0);
int n; cin >> n;
int ans = 2;
for (int i = 1; i < n; i++) {
ans *= 2;
}
ans -= 2 * n;
cout << ans << '\n';
return 0;
}
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