cp/cses/introductory-problems/missing-number.cc
2025-02-26 12:02:28 -05:00

65 lines
1.2 KiB
C++

#include <bits/stdc++.h> // {{{
// https://codeforces.com/blog/entry/96344
#pragma GCC optimize("O2,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
using namespace std;
template <typename T>
constexpr T MIN = std::numeric_limits<T>::min();
template <typename T>
constexpr T MAX = std::numeric_limits<T>::max();
template <typename T>
[[nodiscard]] static T sc(auto&& x) {
return static_cast<T>(x);
}
template <typename T>
[[nodiscard]] static T sz(auto&& x) {
return static_cast<T>(x.size());
}
using ll = long long;
using ld = long double;
template <typename T>
using vec = std::vector<T>;
template <typename T, size_t N>
using arr = std::array<T, N>;
#define ff first
#define ss second
#define eb emplace_back
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
// }}}
void solve() {
int n;
cin >> n;
vec<bool> seen(n + 1, false);
while (--n) {
int x;
cin >> x;
seen[x] = true;
}
for (int i = 1; i < sz<int>(seen); ++i) {
if (!seen[i]) {
cout << i << endl;
break;
}
}
}
int main() { // {{{
cin.tie(nullptr)->sync_with_stdio(false);
solve();
return 0;
}
// }}}