Codeforces Round #793 (Div. 2) C. LIS or Reverse LIS?
- Time : O(nlogn)
- Space : O(1)
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| #include <bits/stdc++.h>
#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
struct PairHash {inline std::size_t operator()(const std::pair<int,int> & v) const {return v.first*31+v.second;}};
#define MAX_N 50505
#define INF 987654321
#define EPS 1e-9
#define ll long long
#define pll pair<ll, ll>
#define vpll vector<pll>
#define vall3 vector<array<ll,3>>
#define all3 array<ll,3>
#define all5 array<ll,5>
#define vall5 vector<all5>
#define vll vector<ll>
#define vs vector<string>
#define usll unordered_set<ll>
#define uspll unordered_set<pll, PairHash>
#define vvs vector<vs>
#define vvll vector<vll>
#define all(a) begin(a), end(a)
using namespace std;
ll solve(vll& A) {
sort(all(A));
ll n = A.size(), l = 0, r = 0, lis1 = 0, lis2 = 0;
bool hook = false;
while(r < n) {
while(r < n and A[l] == A[r]) r++;
ll count = r - l;
if(count == 1) {
hook = true;
if(lis1 <= lis2) lis1++;
else lis2++;
} else lis1++,lis2++;
l = r;
}
return lis1 == lis2 ? lis1 : hook + min(lis1, lis2);
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
ll tc;
cin>>tc;
for(ll i = 1; i <= tc; i++) {
ll n;
cin>>n;
vll A(n);
for(ll j = 0; j < n; j++) cin>>A[j];
cout<<solve(A)<<endl;
}
return 0;
}
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